Is your game crashing?
Most of the time, mods or mod conflicts are the reason your game crashes.
Here's a list of things you can try:
Do you have compatibility mode enabled on gta_sa.exe or samp.exe?
do the following.
-Navigate and right click on samp.exe in C:\Program Files (x86)\Rockstar Games\GTA San Andreas\.
-Go to Properties -> Compatibility.
-Select to Run in Compatibility Mode for Windows 98/Windows ME
-Select Run as Administrator in the checkboxes.
Apply the settings and gta_sa.exe should launch
Model mods still visible after being deleted?
You deleted a mod but it's still in the game? That's because the large gta3.img file is cached on your PC.
Navigate here and delete the entire Rockstar Games folder from it: "C:\Users\woot\AppData\Local\VirtualStore"
(Can't find it? Press windowskey+r and enter the following: "%appdata%\..\Local\VirtualStore")
Still having mod issues?
Delete your entire GTA SA installation. When you re-install it, put it into a different path. For example, usually your GTA SA is installed at "C:\Program Files (x86)\Rockstar Games\GTA San Andreas" - when you install GTA SA, you can select the installation path.
-Reinstall SA into a different directory
-Rename your current SA directory
(Tested as working for me and some others, post if it works or not.)
ASI mods / stream memory fix mods
Stream memory fix mods are not needed anymore, this is a built in feature since SA-MP 0.3.7 - delete all your cleo and asi mods such as StreamMemFix and similar, they often cause crashes. Additionally some asi mods like "fix black roads" cause crashes.
Try deleting all the asi mods from your installation, and then every cleo mod.
Still crashing with an error code?
The error dialog usually looks like this:
SA-MP 0.3.7
Exception At Address: 0x0071A708
[bunch of more numbers and text]
Take the part after "exception at address" and google for solutions. Most of the time, other people before you had the same problem. i.e. in this case I would google "samp crash 0x0071A708"
