Desktop won't load

I have a problem with my desktop not loading. I am not what a person would call a "techie", so please bear with me. I have read all the threads pertaining to this problem, but none appear to be quite the same. First the particulars for my computer: Windows XP Media Centre SDK by Gateway. [I know that I should know more, but can't find out any more info, as can only use the task manager].

Except for the desktop, the computer appears to be running fine. A few days ago, I backed up the computer to "c" drive and did a new install of Windows, following a deletion of duplicate files on computer [silly of me, considering my abilities]. After the reinstall, I began to install the programs that were lost, still OK, but then on a re-start, the desktop would not load. Starts up fine, but then icons appear for only seconds, then are gone. This happens for 5-6 times, and then stops altogether. When I look in task manager, explorer exe. is not running. I put it in manually, but the same things happens. It tries to load desktop, but to no avail. This is the same when I tried the safe mode.
I have put in the latest Java update as directed, run Registry Booster, Cleanup, Advanced Windows Care, System Mechanic6, Zone Alarm [virus and spyware]3x,and have done a Hijackthis, [but no action taken after] and I am still at no desktop.
Could someone please help me. This working with only the task manager is for the birds. I am on dial up [so downloading takes a while] but can still access the internet [obviously], so all is not lost.
Thank you so very much
Shueygal

 

Thank you so very much for all your help. I was desperate, as had to get out some very important information, so once again, I did a back up and reinstalled Windows. Perhaps I am stating this incorrectly, as it is described as a system "refresh", and is backed up to C as a back up of that date. Following this, Windows is installed once again.
Thanks again, and I will be a faithful visitor to this site, its great.
Shueygal