Sugashak, have you tried this...?

FL Studio used to work fine, but now it keeps crashing at startup.

If it doesn't work anymore, but has worked once then you may try to do a config 'reset'. To do this, launch the Reset settings shortcut (Start Menu > Programs > FL Studio 3> Advanced > Reset Settings) & let it delete the needed registry keys.
Note: if you're running under WinNT, the shortcut switch might not work correctly, you might have to use regedit.exe. Take care not to delete any other registry entry! You can still use the Microsoft System Information tool to backup your registry if you're not sure (Important: don't use regedit.exe if you are not familiar with registry, since this may damage your Windows!).

FL Studio crashes at startup.

Some people have reported a crash when Windows is in 16Bit display. There's no reason for FL Studio not to work fine in 16Bit display but anyway you can try to switch to 24Bit (True Color) & see if it corrects your problem. Also according to the same people a problem may occur because of network cards. Again there's no reason for not to work when a network card is installed...

We've also been reported that old display drivers for the Diamond Viper v330 were causing a crash while FL Studio is running. Updating those drivers should fix that.

http://www.flstudio.com/help/html/app_trouble.htm
http://www.flstudio.com/help/