I don't have a direct solution for the Start button/Mouse problem, but can you use the keyboard to get access? Try tapping the Windows key or using CTRL+Esc to access the start menu.
If that works, the shutdown would be CTRL+Esc, Tab, <up arrow>, <right arrow> and program access would be CTRL+Esc, <up arrow>, <right arrow>.
You should also be able to Run programs directly. For example, tap the Windows key+R and type in winword then hit <enter> or click OK to start Microsoft Word.
To diagnose your Start button/Mouse problems, try starting your computer with a 'Clean Boot', (see the Microsoft Support articles below). If this solves the problem you'll have to discern which background programs and/pr services are causing
the problem and disable them.
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/kb/929135
Perform a clean startup to determine whether background programs are interfering with your game or program
http://support.microsoft.com/kb/331796
- "Have you tried turning it off and then on again?" - Roy from 'The IT Crowd' (Emmy award-winning British comedy)