Windows 7: black screen after logging last for about 6 minutes only white arrow

Hi,
I have the following problem on my windows 7 professional 64bit and on win 7 starter as well, the black screen appears after logging in and lasts for at least 6 minutes. After spending some time dealing with this issue i managed to discover, that problem disapears when i disable CNG key insolation service, but this service is needed for WLAN card, and manual running of services like the one above or automatic wireless connection configuration service after any boot is just very anoying. I think that the problem might appear with the latest windows updates (october, november 2010), or some new malware is active. Nevertheless I need help! The script that runs required services after logging is not an option. It is important to identify the source of the problem and the way of geting rid of it. Any hints or solutions kindly welcome!
sorry if my english isn't correct... hope i'm understandable ;D
Regards,
Greg