|"I tried to reinstall my OS but still have a same problem"|
How did you try? Do you have an install CD? Did you boot to it and try to do an over-the-top Repair install?
What was the exact error message?
Have you tried to boot into Safemode or Last known good configuration? Access these options by tapping F8 while booting.
Goin' Fishin' (Some day)