PC configuration:core 2 duo 2.93 ghz 3 gb ddr3 ram.. 320 gb hard disk... nvidia 8400 graphic card...

Is it possible your missing files so its taking longer? What OS are you using? Have you been doing a lot of updating lately?

I'm using xp sp2 and win 7 enterprise... I didn't update anything...

If both OS's are giving you problems and your booting slowly then there could be one of many problems causing it. Is this a recent problem that just started after installing another OS? You are aware that there is some incompatibility between those OS's and disk drive access and handling.

Nah it is not like that... I m using both operating systems for about 7 months... but I encountered with this prob recently... the actual problem is that... when I swith on the cpu... black sceen appears... and this happens before the os choosing screen appears

Ok, have you did a memory test lately and checked your hard drive for errors and also did a defrag? Is your hard drive running low on space?

Hmm well... 20 gb disk space is still left... out of 320 gb space... but it was running in this condition... this prob has appeared now... can't it be due to some hardware problem

For one thing your too low on the hard drive space. Going below the 10% mark on any hard drive using windows is not a good idea. The minimum for you would be 32 gig.

Try running the other tests and doing a defrag. Also get rid of unwanted files or programs before doing the defrag.

If you have a lot of pictures or moveis consider getting an external hard drive and moving some of it off your primary drive. It should run a lot faster after you do that.

Well I will follow your suggestion... well thnks for this