thanks, here is the details:

system:
Dell Latitude D530
Windows vista business
RAM: 2GB
Processor: Intel(R) Core(TM)2 Duo CPU T7250 @ 2.00GHz, 2001 Mhz, 2 Core(s), 2 Logical Processor(s)


The problem started after once I had to shutdown the system with power button. Nothing else i could recall I did.

Best,
Deependra