Need help. Built new system 6 months ago and have had no problems until today. Running AMD 64 X2 3800 on Abit KN9 SLI with a pretty standard system. Most of my settings are in default mode and I do not attempt overclocking or aggressive settings. During boot everything is fine for the first second or two . When computer reaches the memory test, it freezes and does nothing for 20 minutes. Eventually it will finish like it was just waiting on something and I get a CHECKSUM ERROR. I have not made any changes or upgrades in hardware or software. Have tried clearing CMOS, removing power cord, removing CMOS battery, loading default values after I finally get past MEM test, but nothing seems to work. I don't know where this came from.