Asus Rampage II + OCing and problems

Hi,
I'm running Vista x64 Ultimate on my computer. I'm using the Intel i7 940 CPU, 6GB of Corsair RAM, and the ATI 4870 gfx card. Whenever I select the OC memory function in the BIOS and have it OC'd to the 1600 option, when Vista loads back up, if I download a file using firefox, the "scan for viruses" on download completion just hangs and the program is unresponsive and won't even close from Task Manager. Has anyone experienced similar problems with the OC options on the Rampage II when using Vista x64?

Thanks!

yes i am using the Mighty RAMPAGE II EXTREME II EXTREME on vista 64bit ultimate u just need to update ur bios to the latest which is 1504 download it from asus web than use asus update to flash ur bios and make sure u update both bios p.s o.c the memory should be done once ur o.cing ur cpu not alone and make sure u keep u voltage under the 1,6 red line t.c the board is outstanding enjoy it man t.c all bye bye.