If the file is over 2Gb and this caused the corruption you could try the PST crop tool here:
http://support.microsoft.com/default.aspx?scid=kb;en-us;Q296088
Apparently running scandisk on the partition where the pst is stord can also fix it.
If the file is really important there are loads of tools on the net that claim to fix corrupt PSTs but you have to pay for them