Problems with PST Files
The only issue most people have with PST files is that they become corrpt. It is possible to do a PST file repair using a variety of methods, depending on the severity of the damage. The first task is to find out where your PST files are stored. By default, they can be found in “C:Documents and SettingsUSER Local SettingsApplication DataMicrosoftOutlook”. Be sure to substitute your Windows login screen name for USER when typing in this directory. The default filename for your PST file that is hosting your current mail box is Outlook.pst. There is also an archive file available, known as Archive.pst. There is no way of telling if a PST file is corrupt based on visual inspection. In almost all cases you will know the pst file is corrupt becaue when Opening up Outlook it will tell you that.
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Microsoft Outlook comes with an automatic repair method and an external repair kit for fixing Outlook PST files. When Outlook is opened, the program will notify you of this problem, and then attempt to fix the PST file automatically. Outlook will in most cases try to do an automaitc repair of the PST file and you should let it try before having to use the external free Scan tool. In the event that the automatic repair fails to fix the Outlook PST file, you will have to open the Inbox Repair Tool located in C:Program FilesCommon FilesSystemMSMAPI1033 and search for the Inbox Repair Tool, under the filename Scanpst.exe. Click here to see the exact steps.