Well i used to have the same problem once on my OLD pc....
what it was cause by was... by a lot programs who had changed a LOT Settings of Windows while running...
so simply just open Task Manager.... then go on "Prosseces" Tab, and start stopping some useless...
what I used to stop was things like "CCC or HydraDM, Fast, Browse, egui"... CCC and HydraDM were by my Ati Radeon's Graphics Drivers...
Fast was by a program which was scanning things.. and egui must was by Nod32 i think...
just try doing that before opening the sa-mp... try to remove the most with Mem Usage: 50k+.... then I hope it will work..
if it DOES Work by doing that, then simpy un-install the latest software/applications you had installed, until you find out the way it wont crash. or else use program like CCleaner to fix registry errors, and remove some start-up activities.... (i use RegistryFix for that, but done once on CCleaner too... as programs work for the same feature)