OS = Operating System (XP/Vista/Win7)
Generaly if the Game worked before and suddenly stops working properly a driver or other config may have changed (updated, etc) which the .set file doesn't like.
Deleting the GTA_SA.set file (which contain current configs) may allow the game to adapt to the new <whatever>. The .set file is created when ending game play each time you have a successful exit.
Again, DYOM is a modification of the normal Game programming.
If you play the regular Clean (Un-modded) game do you have the mouse problem?
Some reference topics and quotes:
MOUSE NOT WORKING:
Have you tried running the game in Windows 98 compatibility mode? That's the first thing to try when dealing with mouse issues on Vista.
Maybe it's got something to do with the affinity of your CPU if it's a quad core:
Start the game, hit Ctrl+Alt+Del (this minimizes the game and opens up Task Manager), go to Processes, right-click on gta_sa.exe > Set Affinity > Uncheck all except CPU 0.
Now return to the game and see if you can click again. Gta sa mouse problem solved! GTA San Andreas Mouse Freezing
mouse freezing bug. Weird Mouse problems mouse problems,
mouse not working in SA Mouse not working PC Mouse Not Working…Help http://www.gtaforums.com/index.php?showtopic=299949
] Mouse not working, [/url] Will not pan in game, no click in menu. Mouse not working, This post has been edited by lil weasel on Saturday, Mar 31 2012, 10:59