I am burning JPEG pictures using directCD onto a CD-R from my XP laptop computer. I close the session to read on other computers and I can read it on my W98 desktop with no problem. I take the disk to the photo lab and they can only read part of the data. I create a directory and place 108 pictures (jpeg files) in it and they can only read 30. If they take the disk to their computer for customers to use it reads all.
It is very strange to me that their main computer can read some of the files but not all.
This has been an intermittent problem but would like to have help identifying the problem and see if I can do anything different on my end to resolve.
Any help would be greatly appreciated.

Disks burned using "DirectCD" can only be read on a computer that either has DirectCD [includes the UDF Reader] installed, or has the "UDF Reader" alone installed.
The UDF Reader is included on all CD's burned using DirectCD, and when such a CD is put in a CD-drive on a PC that has neither of the above, then "Autoplay" will result in a request for permission to install the UDF Reader.
Once installed the PC should be able to read the disk.

You say:
"I close the session to read on other computers"
Which doesn't make sense.
If your using DirectCD, then there is no need to "Close the session".
Aha, I get it, you're using CD-R's when you should be using CD-RW so they can be used like a giant floppy.
Not sure what would happen if you use the [not recommended] CD-R's with DirectCD.

DirectCD prepares a CD-Recordable (CD-R) or CD-ReWritable (CD-RW) disc so you can directly copy files to it in much the same way that you copy files to a floppy disk or removable drive.

Ejecting a DirectCD Disc You can not just eject a DirectCD disc (in fact, the eject button may be disabled). Before you eject, Direct CD must update directory entries and prepare the disk for reading. When you eject a CD-R disc, you have three options. The option you select depends on how you plan to use the CD. To eject a CD-R disc: 1. From within the Direct CD window, click Eject, or from Windows Explorer, right-click the CD-Recorder drive letter and select Eject. 2. The Eject Options dialog box appears, select the option you want: • Leave As Is - Leave the CD as it is so it can be read and written to as a drive letter. Standard CD-ROM drives will not be able to read the CD. Only computers with CD-R or CD-RW drives can read the CD. Use this option when you plan to keep adding files to the CD and you do not need to give the CD to someone else to use. • Close to UDF v.1.5 - Close the CD to the UDF v.1.5 format so that it can be read on most CD-ROM drives after installing a UDF v.1.5 reader. Use this option when you need to give the CD to someone who has DirectCD 5.0 installed or who you know has a UDF v.1.5–compatible reader installed. When you make a CD using DirectCD, it automatically copies the UDF Reader for Windows to the CD. When you insert the CD into a CD-ROM drive, the reader will automatically ask if you want to install it. • Close to Read on Any Computer - Close the CD so that it can be read automatically in most standard CD-ROM drives. Use this option when you need to give the CD to someone else to use and that person may not have a UDF v.1.5–compatible reader installed. CD-ROM drives under other operating systems, such as Unix, Linux, and Macintosh, can also read the CD without using any special reader
http://learn.dccc.edu/~lori/tutorials/burning.pdf

PS If you are taking the CD to a third party the best compatibility is to just write a single session and then close the CDR rather than use packet writing at all.

Try them in batches of thirty or less.

And, are you sure they all are jpegs?

Is there some size limitation with the program?

Are these jpeg's from your digital camera, for example?

Edit:
Paul K has it rightly,

Cd-r's are what to use in this instance. I would not expect any local photolabs to be able to handle cd-rw's or even common dvd's!

Make finalized cd-r's for use anywhere other than 127.0.0.1 ;)

While I do appreciate your input, what seems to have been overlooked is the fact that their drive does read the CD-R but not all the files. For example, I have a directory that has 108 files in it that they can only see 30.
I have been using CD-R's for about 3 years to write jpeg files (from a digital camera) onto a CD-R and send to photo lab for printing. I have put over 300 files on a CD and had no problem at the same photo lab.
I create directories (4 x 6 - 1 per, 5 x 7 - 2 per etc.) and drag them using windows explorer to the CD drive. When I eject the cd it gives me options to close the session or to leave open. I have always closed so that other drives can read it.
The photo lab has two pc's. One inside the photo counter hooked to their Fuji photo printer and the other is out side the photo lab counter area for customers to use. The customer pc reads the cd correctly but the labs main pc does not. I could use the customer pc but the software does not break the files into separate directories that I created to identify the size and qty of files I need printed.
Anyone with knowledge to help me with this would be greatly appreciated!

Didn't know that this is a change that has happened. Is there any obvious difference between the files that are seen and not seen - particularly such things as strange characters in the file names or just simply long file names.

No differences between file types or file names and no strange characters (only letters and numbers - 16 chariters total). They are assigned by my camera and I add a suffix.
Today I noticed that my pc at work displays the same problem. My laptop running XP reads all 108 files. My PC at work running XP cannot read all files. When I do a properties of the cd in my work PC it states all 700 megs of space is used and no space is available on the CD. When I select the files and list the properties they only list 38 megs total. When I put the CD in my laptop and list the properties of the CD is states their are over 600 megs of free space.
Is this a software issue? Should I try a different burning program?
Help!

The hit and miss of different pcs being able to read and not read does seem a bit odd and it would be nice if one could find a common denominator. 700 meg is at the upper limit of capacity obvioulsly but then why just some of the files with the majority becoming "invisible".

Are you sure that all the jpegs are still actually usable even when they can be identified?

I doubt it being a software problem and more likely to be a failing/dirty CD drive or bad media. Possibly CD check from http://www.elpros.si/CDCheck/ could help identify any problem files; possibly not.

I would try burning the files as a single session and closing it rather than use the packet writing method rather than start switching software. AFAIK EasyCD is the only commonplace software that burns packet-writing to CDR using DirectCD, so if you were to switch to Nero, for example, you would have to burn in sessions in any case unless you were to use its packet-writing utility InCD, which only does this with CDRW media.

Paul,
Good post above and thanks for the link.

Burning a data disk onto cd-r, or as you put it, a single session, is probably going to help. You mentioned disk quality as well and is a valid point.

Let me add that some cd-rom's (readers or writers) of differing quality may be at fault as well. My laptop (Toshiba) has an internal cd-rw. Factory disks with extremely few blemishes (scratches, dulling of sheen), does not read the disks at all. Take the same disk, burn a copy of it in another pc and the copy reads fine in the Toshiba. What I should do is try my dvd-rom installed to the laptop and try the same originals to see if it is a weak cd-rw.

Just a mention of even more variables to consider... :) If you have other drives on the pc that isn't reading properly, try the other drive.