firefox vista problems

I have installed firefox 3 for my new vista operated machine. I get the
following error message:

Could not initialise the application's security component. The most
probable cause is problems with files in your browser's profile directory.
Please check that this directory has no read/write restrictions and your hard
drive is not full or close to full. It is recommended that you exit the
browser and fix the problem. If you continue to use this browser session, you
might see incorrect browser behaviour when accessing security features.

I have tried following the steps suggested by Mozilla such as editing the
user profiles, which has not worked. The programme will not even open for me
without crashing.

I have tried other browers and they do not even install.

I am convinced that this is a problem with Vista - that it's somehow
conflicting with the browsers.

I have tried to ask for remote assistance over MSN and this also does not
work!

How can I fix these problems to make Vista work?

I much prefared XP - it was far far easier to use and all my software
worked with it.