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#11
That makes it sound like a software problem. However, booting from a Live CD also eliminates hard drive. The OS is loaded into RAM from the CD.
Safe Mode makes it sound like a hard drive issue, as does the fact that the problem started in slowly, and got worse.
Try testing your hard drive again. What program did you use? See here: HD Diagnostic
Also, check for bad sectors on your C drive. Open an elevated command prompt and enter chkdsk /r. Reboot, and let the scan complete.
When it's done, go to Start>eventvwr.msc>Windows Logs>Application Logs. Sort the list by Source, and paste the results found in Wininit to your next post.