PC freezes after boot

Problem: PC freezes also in Safe mode

When in normal mode, it freezes just after login, and when HDD is taken to another PC, and scanned for viruses and spyware there is blue screen message Physical memory dumping.
Also other symptoms and diagnosis: Boot CD ERD Commander do not show folders, Windows Instalation CD in repair mode check disk with no problems found, and HDD test is successful.
Solution from the web that helped in this case is to defrag HDD:

1st: you have no choice, you need to restart your pc. 2nd: go to Start Menu->All Programs->Accessories->System Tools->Disk Defragmenter 3rd: click analyze. it takes time to analyze, so be patient. When it says "you need to defrag this volume" proceed to 4th step. 4th: click defragment. it also takes time to defrag, need more patience here.
When it say memory dumping, your memory can't take anymore the error of your hard disk. The volume of your hard disk is messing up. The volume need to be fix. You won't let your memory card suffer from all errors inside your hard disk don't you? This error won't show up again if you defrag your hard disk once a week or twice a month.
If the error still occur even you maintain to defrag your hard disk, Oh men you need to add an additional memory card because your memory is insufficient. "can't handle large programs"
http://www.anetforums.com/posts.aspx?ThreadIndex=28891