when i start up my comp the install hardware thingy appears and asks for drivers for some thing with an yellow ! called "mass storage controller".
what is it and what drivers does it need?

Install "Unknown Device Identifier" got from http://tinyurl.com/bcbhn to find out what that device is.

Mass storage controllers are such things as SCSI, RAID, SATA, Fibre Channel controllers on a motherboard or PCI card and which are typically used for adding hard drives of one sort or another to your system but not by using the ordinary two IDE/ATA channels.

Such a card or controller needs the drivers installed before it can be seen and thus before any storage devices on the controller can be seen. Your mobo or pci card should have come with the relevant drivers. If not go to their website to grab them.

On my PC...
The only entry that "Unknown Device Identifier" lists as "Mass Storage Driver" is a "DigitalCamera" [doesn't identify which of the two I have installed this refers to but it links to a Google search result that lists "Vivitar".]

Hmmm, this program will backup drivers one at a time.
Might have a go at that.
It will also help with finding drivers [does a suitably worded Google search].

Most cameras nowadays attached via USB are de facto removable drives and may thus be designated as needing a "USB Mass Storage Controller". Add-on internal cards are usually designated as needing a "PCI Mass Storage Controller". Motherboard controllers would not normally have any prefix.

Followed a link to "My Drivers 3.11" at http://www.zhangduo.com/driverbackup.html and installed it for a 15 day free trial.
It will "Collect All" info on all drivers installed, then "Backup All" drivers in one go.
Mine took about an hour [forgot to time it] to backup all 64 drivers, each to its own folder in a folder location specified by me [on a CD-RW disk made with "DirectCD"].
QUOTE
"You can restore all drivers by clicking a button.
Once after a reboot, all the drivers will be re-installed and will function well.
You may also choose to backup a particular driver or all the drivers with an EXE automatic installer. If you chose to backup all drivers to an EXE installer, you may simply double click the installer and all drivers will be restored after a reboot.
It is also capable of serving those people to find and install the appropriate and latest drivers for their hardware devices. My Drivers identifies almost all hardware devices, reported information includes device model, device manufacturer, chip/chipset manufacturer, OEM name, OEM vender. Over 58,600 drivers information and manufacturers and venders information are embedded with the software. You may easily find a driver that will work for a certain device by PnP ID fingerprint comparison, and a compatibility test will be performed before installing a driver that will be downloaded from the Internet."