I've hit a brick wall and really could use some help..

I have Vista OS and using Outlook 2007
All of sudden I'm having problems opening Outlook.
I get a message that cannot open file outlook.pst. Errors with file:
"The file C:\Users\gflefel\Appdata\local\Microsoft\Outlook\O utlook.pst
cannot open and has an error. Run Scanpst.exe" (something like that -I can’t
repeat the error message now cause outlook now opens in a new pst file I
created)

When I tried the Outlook 2007 Inbox repair tool using Scanpst.exe, I get
another error message on phase 6 (out of 8):
" An error has occurred which caused the scan to be stopped. No changes have
been made to the scanned file"

All programs were closed before the scan. Nothing except the IE.

Thanks to many posters here, I managed to understand somewhat what's going
on. So I added another Outlookpst file and named it differently (Outlook08).
And I made it the default file. So for now, I can at least receive emails &
work using outlook (but no contacts or old emails). Thanks guys.

Both old pst and new pst files (outlook08) are in the same location and both
show on the account settings in the data management file option (but the
outlook08 is the default). So when I try importing the data from the old to
the new, it tells me the old pst file is in use. Outlook is open and I am
using the new outlook08 profile. So what am I doing wrong to import the data
and is there another way to repair my old pst file since the Scanpst option
is not working.

Do I remove the old pst file from the Data file management option? I am
concerned incase I cant bring it back (keeps giving me errors if I try to
make it back to the default file)

Any help is much appreciated.
Thanks in advance
George