Apologies doctadrone. Allright. Try this, Download the following file
http://www.dougknox.com/xp/fileassoc/xp_exe_fix.zip
Save it to your desktop.
Hit ctrl + alt + delete
Hold control, click on file and select New Task. This should open the command Prompt.
Type REGEDIT.EXE into the command prompt, hopefully this will open the resitery editor for you.
Click on File in the registery editor and then on import. Locate the file you just downloaded and select open.
Let me know how that goes