My machines configuration is Intel i5 750 2.66 mhz, 4 gb 1333 mhz ram and 1 gb leadtek gts250. When i use Boinc, every day it crashes my windows 2-3 times. I get memory management error or IRQ error. I installed all latest drivers but can not solved the problem. What can i do for solve this ?

which projects are you running right now?

you might face a problem with a special project not with W7..

Seti
Einstein
Milkway
Cosmology

http://www.boincstats.com/signature/user_2218221.gif

does not fit for my experience - i got 4 hosts running W7 and the only project that's rarely showing troubles for me is YoYo and only on a PHENOM-II.

you should try to figure out which WU errors out - unless you got a real problem - then it's about time to go for testing your setup!

but i get no error to catch

Memory management errors? IRQ errors? Are you sure it's BOINC? Sounds like hardware issues to me. Have you actually tested your memory?

Yes i have tested all hardware parts. This happens only when boinc runs.

First, make sure you have turned off automatic updates - the ones that automatically install updates, and restart your computer, causing GPU tasks to be terminated and the system to sit idle at the logon screen.

Check your error logs for problems.

You should check your RAM, but you might want to have a look at your Bios too for incorrect settings - I would suggest you reset the Bios and reconfigure it again.
Although you could check your IRQ pairing/conflicts from Device Manager and Drivers, my guess is that you have some sort of legacy device that is causing a problem. Uninstall anything that is not essential to boot the computer and then add one device at a time until you have identified the cause.

Make sure the videocard is tight in its PCIE slot, a loose one will wobble when the fans spin fast and cause crashes.

IIRC, this is a gpu problem. Some users at Milkyway posted something about drivers and VPU.