You might want to have a seat before you read on...
I have actually solved the problem... with help from a PC forum :-o
:-P
I posted the problem, they asked for a HijackThis log, posted it back and they told me to fix:
O4 - HKLM\..\Run: [DisplayTrayIcon] C:\WINDOWS\System32\TrayIcon.exe
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\System32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\System32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [C-Media Mixer] C:\Program Files\PCI Audio Applications\Bin\AudioRack.exe /MixerStartup
O4 - HKLM\..\Run: [AudioDeck] C:\Program Files\VIA Technologies, Inc\Audio Deck\ADeck.exe
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [TkBellExe] "C:\Program Files\Common Files\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - Global Startup: GetRight - Tray Icon.lnk = C:\Program Files\GetRight\getright.exe
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office\OSA9.EXE
O4 - Global Startup: VIA RAID TOOL.lnk = C:\Program Files\VIA\RAID\raid_tool.exe
Which I did (except for GetRight). Rebooted and no dir opened :-D
--edit--
Removing the raid_tool.exe on it's own didn't have an effect, so it must've been something else, or partly something else...
--edit2--
Not that I didn't have any faith in you guys, far from it, but I didn't seem to be getting anywhere at the start (yesterday morning) so I posted on another forum to see if they were stumped. I really hoped that they would be :-D