When I had the user track problem, I sent an email to the Rockstar tech-support, detailing what I did, more or less what was written in this thread. I just got a reply from rockstar.
Here it is:
Thank you for contacting Rockstar Technical Support.
To use custom soundtracks in the game, you will need to create shortcuts,
or copy the MP3 or WMA files to the game's user tracks folder
Shortcuts should be placed in My Documents\GTA San Andreas User Files\User
Tracks" Please ensure that My Documents is set to it's default location.
Once the shortcuts to MP3 or WMA files have been created, open the game and
Select Audio Setup then click User Track Options
Click scan user tracks and the game will verify the track shortcuts. A
message will be displayed in the bottom right corner of the screen if the
tracks were scanned successfully
Choose the 'usertracks' radio station and you should now be able to listen
to MP3 files in the game. Please note that the game will continue to play
the current advert until it is finished before it plays the next track
Also ensure there are no other background apps open as some music utilities
may prevent the use of MP3s if they are open as a background app
Please be sure to delete all previous correspondence when replying. This
will help us to process your response in a more timely and efficient manner.
Rockstar Technical Support"
I actually feel insulted reading the reply, since I've stated that I did everything the manual & readme file told me to do. I'm surprised that didn't add the "use your right hand to hold the mouse, and move your cursor on the ..... "
If this is the kind of Tech-support we can expect from R*, then 75% of the users in this forum gets my vote for the R* tech-support replacement