problem with Windows Explorer

When I go into My Computer on this laptop, I can explore the DVD drive OK, when I put my thumb drive in, it comes up right away and I can browse thru it OK. But if I double click drive C: it opens the dialog window saying "what program do you want to open this with?" and Explorer isn't listed. I have to click "Browse" and navigate to Explorer in the Windows folder. Then I can explore C: just fine, temporarily. Explorer doesn't stay in the list, and the box for "Use this everytime..." is always grayed out.... any ideas?
Thanks.

Oh yeah.... Windows XP Home SP2... the same things happens if I right click drive C: and choose either Open or Explore. Open With... is not an option, it's not even listed in the right click menu.
:confused

 

Anybody? Anything?
:confused
:cry

 

Did you try this?

http://support.microsoft.com/kb/321186

 

No, I spent some time searching the Knowledge Base but couldn't find anything useful, and I had problems just trying to figure out what to type in the freekin' search box... So, THANX! I won't be able to try it until tomorrow, but it sure looks promising. It's alot more than I have now anyway
Thanks, I'll let you know if it works.