This may help you:
http://support.microsoft.com/?kbid=259416
This information also may help you:
This fix also applies to Outlook, other programs that store passwords in the Protected Storage System Provider sub branch of the Registry. It also corrects some issues with Internet Explorer and Autocomplete.
This is caused by a damaged Registry key. To Remove the broken Key in Windows® XP
1) Click Start, click Run, and then type regedt32 in the Open box.
2) Locate the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Protected Storage System Provider
3) Right click the HKEY_CURRENT_USER\Software\Microsoft\Protected Storage System Provider key, and then Select Permissions.
4) In the Permissions for Protected Storage System Provider dialog box, click the Advanced tab. Make sure that the <Username> has Full Control access. Select "Replace permission entries..."
5) Click OK.
6) Repeat steps 3 through 5 for each subkey that is listed under the Protected Storage System Provider registry key; otherwise, you may receive the following error message when you try to delete the Protected Storage System Provider key:
Registry editor could not delete the key currently selected. The key or one of its
subkeys does not give you delete access.
Note: The sub keys under Protected Storage System Provide will look something like this:
S-1-5-21-1085031214-1202660629-1708537768-1003
7) At this point, you can delete the Protected Storage System Provider key by clicking Delete on the Edit menu. If you prefer, you can first export a copy of this key, and then delete the key. To export the key, right click the Protected Storage System Provider key, and select Export. The exported file can be re-imported by double clicking on it.
8) When you click Delete, you receive the following message:
Registry editor will delete the currently selected key and all its subkeys. Do you want to continue
the operation?
Click Yes to finish the process.
9) Start Outlook Express. When Outlook Express checks your mail account(s) you will be able to re-enter your password(s). This process repopulates the Protected Storage System Provider registry key with the correct information for that computer's SID.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q264672
