installation vista upgrade windows explorer

I have a Motion 1400.
I upgraded to Vista using the Microsoft DVD. I did not use the full install.
Vista comes up but is hung up on searching and finding a solution to a problem with Windows Explorer. The computer is unable to do any more than stay with this. Let me explain.
A box appears saying that there is a problem with Windows Explorer and that Windows is looking for a solution.
A minute later, a box comes up saying that the Windows Explorer does not work correctly and that Windows was closing this program.
If I do not click the cancel box, the computer seems to stop. By this, I mean that the clock stops.
When I click the cancel box, the process starts over again and again, and on.
At the beginning, while Windows looks to correct the problem with Explorer, a box appears and asks for the original disc for Office 2003. This was installed by the University administrator. I have an Office disc but cannot install it on Vista. When I cancel the task, the box does not reappear.
Only the Windows Explorer box search-for-solution box appears.
I read on one of your responses a way of getting into the BIOS as a way of accessing the Vista DVD for a system install. I have some concern doing this without guidance. At my level of expertise, this is not for the faint hearted.
Is there a solution to this problem such that I can use Vista? Can I do a full install of Vista now? If not, how can I go back to XP? Will I have to reformat? I hope that I do not have to reformat the computer and reinstall XP.
Look forward to your wisdom.
Steve S