I have a Pentium 4 2.53 Gb with a GeForce 2 MX 400 video card,and Windows Xp OS. Now,here is the problem...
I installed and played Grim Fandango,an old adventure game.Then i uninstalled it,and after running the system diag i noticed that somehow the Direct X version was an older one than the one i had(i had Direct X 9.0a and after checking my system i had Direct X 5.0 or something like that,i'm not very sure.)I also noticed that my video card memory was 16 MB,and not 64 as it shold have been!I tried to play a new game but i couldn't because it kept telling me that my video card is low on memory!I installed the Direct X 9.0b,and the updated drivers for my video card,but...nothing!My video card memory still is 16 MB,though when i open my computer,when it is checking the programms, it says: NVidia GeForce 2 MX?MX 400 64MB memory.
What is going on????????

P.S:I don't know if Grim Fandango changed the Direct X version,or that has to do anything with the memory problem.The problem could be older but i discovered it just yesterday...

Any ideas?
Thanks in advance!
(Sorry for any mistakes!I don't speak English very well!!)

If you were able to play the new game before the problem happened, then update your antivirus program with the latest files and do a virus search.
Also, D/L either Spybot or Ad-aware, and remove all spyware.
Then, start in Safe mode, remove all video cards from Device Manager, restart, and reinstall its drivers.
Finally, D/L either AIDA32 or Belarc, and check your system's properties.

If you did not play the new game before the problem happened, then you may need a video card with more memory than 64MB to play it.

It sounds like during the uninstallation of this game your configuration was set back to a previous arrangement, probably by reverting to saved copies of the the configuration files [the Registry files being the main ones].
This can be tricky or simple depending on how much you know & understand about your software.
(I doubt if it changed your DirectX files, just the DirectX configuration information [which would cause a mismatch between the files and the configuration! OUCH!])
On second thoughts, it probably installed DirectX 5 with the game and failed to restore the previous files when you uninstalled it.
You need to be able to restore your files [including the configuration files] to exactly the way they used to be before you ever installed this game!
I assume your hardware is unchanged since the installation.
Which Operating System do you have?

Here are some notes I stored away on this topic:

BACKUPS
The easy way to recover from all software [including configuration] problems [without even having to discover the cause], is:

1) As you proceed forward in time, make backups of everything on your C: drive.
Do this at regular intervals, particularly before making software changes [un/installing programs or changing configuration] and keep a log of all this.
2) When you hit trouble caused by a bad configuration change and no hardware or software changes have been made, use "scanreg /restore" [in Win98] to restore a previous good configuration.
3) When the trouble involves more than just the configuration, but involves the files [including the configuration perhaps] but no harware has been changed [this is important because the software must match the hardware], then:
----------------------------------------------------------
Re-format the C: drive and restore your latest good backup.
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The software will "jump back" to the way it was when the PC worked.

It helps if you keep the C: drive "lean & mean".
I move as much as possible off the C: drive.
The "Windows" & "Program Files" folders account for 95% of the used space on my C: drive.
All the data that changes day by day are re-homed on another physical drive [although another partition would do].
When I "jump back" I still have up to date:
a. My Documents.
b. E-mails for all identities.
c. Internet Explorer Favourites.
d. Temporary Internet Files.
e. I have not yet found a way to re-home the Microsoft Address Book so I keep a backup of that with the others. It's normal home [in Win98] is C:\WINDOWS\Application Data\Microsoft\Address Book.