Can ants inside my laptop permanently harm it?

A little while ago (late june 2010) i set my laptop on the floor overnight and when i came to get it the next evening-ish i discovered that ants had been crawling around everywhere around the area. Tons of ants had even crawled into my laptop. I turned it on the side and began shaking it and many of them fell out and i killed them with bug spray. I also left my laptop on a table and sprayed bug spray close to the laptop (actually on the table). They seemed to all go away and the laptop worked fine. However now (late august 2010) my laptop has begun to make noises. It sounds like maybe the internal workings of the laptop are frying (sort of like a crinkling sound). I immediatly turned it off, took off the power supply, and the battery. however i think the noise is still coming regardless (not entirely sure...i'm scared to check). I know that ants are attracted to electrical impulses and electronics. But could my encounter really be due to the ants. It was working fine before. wouldn't it have broken back then if the ants were the cause??? please help. i don't want my laptop to die. and i prob. really should try to save important files before (hopefully not) anything else happens. Any comments, info, or suggestions??