I've tried so many things but itunes is not working

Question

I tried to install itunes 5 last monday but it did not install successfully and I encountered many of the error messages people have already detailed. (I'll know next time to check these boards before faithfully clicking on the download button - I could have saved myself so much hassle!)
I followed the instructions in Dimitry's post - uninstalled bonjour/quicktime etc and then managed to do a system restore. The system restore went ok and itunes seemed to be working but it made the computer run incredibly slow and messed up the 'Ahead Nero- Burning Rom' program.
On saturday, we ran a defrag to see if that would speed up the computer - that took nearly 7 hours to run! I then did another system restore which has made the computer run properly. But itunes did not work, so I tried to reinstall it from the disk that came with the ipod. It gets to the end of the installation and says that a newer version is stored on the computer and so cannot install.
I then picked up a download for itunes 4.9 from one of these threads and tried to install that version, but again get the same message that there's a newer version on the computer so cannot install.
I think I have itunes 4.8 on the computer, but when i try and open it, I get a message that itunes cannot run because some of its required files are missing and i need to reinstall itunes! (I don't think quicktime is installed correctly on the computer either as i get an error message - is the standalone download on the apple site safe to use?)
I think i need to completely uninstall itunes and then reinstall it, but i'm scared of losing all my music. I cannot back my music up as the burning-rom program is not working - i tried reinstalling it, but i need to enter a serial number to complete the installation, but i don't have one as it all came in the bundle with the computer.
Any advice greatfully received!

Answer 1

Hi B
I meticulously followed the instructions but I still haven't been able to completely uninstall itunes and the ipod.
When I right-click on the bin folder in the ipod folder in program files and then choose delete, I get the following message:
"Cannot delete iPodServiceLocalized.dll: Access is denied. Make sure the disk is not full or write-protected and that the file is currently not in use."
When I right-click on the Quicktime folder in program files, I get the following message:
"Cannot delete QTTASK.EXE: Access is denied. Make sure the disk is not full or write-protected and that the file is currently not in use."
When i open the windows installer cleanup tool I cannot see itunes/ipod/quicktime in the list.
I suspect this is something to do with administrator rights? How do I log in as an administrator? Only me and my husband use the computer, but we don't log in under any different IDs or anything, we just switch it on and start using it?!
I tried installing 4.9 from one of the other threads anyway, but I still get the message that a newer version of itunes is installed so it cannot continue. The itunes in the ipod program file shows as 4.8.0.
Look forward to your advice again.
Thanks, Amanda.