Hard disk sir i am using 80 gb sata hard disk which has 3 parititions i have formated one parititon in ntfs that is the primary one and the rest in fat 32.the problem which i face is that sometimes my cpu does not read the hard disk or programs run rather very slow.i hit the cpu like we used to bang our televisions and it starts working fine for days.what can be the cause of it????

Sounds like loose cabling within the case. Power down the system. Unplug the power cord from the PC. Open the case. Check every data cable & power cable in the PC. (Need good connections).
SATA hard drive data cable & SATA power cables can easly come loose, unlike IDE cabling which are unlikely to come loose. Banging the PC case will cause damage sooner or later! Run windows system defrag on the drive. (Also run windows Disk Cleanup). This should help speed up programs running slowly. Like a TV, PC's get dusty & dirty within the PC case. Once every couple of months, you should open the case & blow out any build up of dust. (Check connections before closing case).
If you're SATA data cable seems snug. Try cleaning the cable contact ends with alcohol & a cotton swab. (Both ends of the cable). Allow time for the alcohol to dry before reconnecting.

Good Luck!
M