Thanks for your suggestions, I've basically tried all the scans, anti-virus, spybot, superantispyware, ccleaner etc. Auto Arrange is switched off as well.
None of this has fixed the problem, my desktop icons are still not where they should be on boot up & the quicklaunch bar is absent. The desktop still glitches & re-arranges itself sometimes for example when I have a lot of windows open & I hit the show desktop button from the quicklaunch bar.
Could this be a graphics card issue I ask myself??