Occasional emails will not delete immediately from Outlook 2007 client

I have a user that is having problems deleting emails from her inbox.  She is able to open and read the mail, but when she attempts to delete the email nothing happens.  However, about 30 minutes later she finds the email in her deleted items.
This does not happen on all emails, it does not happen on a specific email.
There are no size quotas for her account on Exchange.
I've checked her event viewer and she has no errors.
Are there any settings in Outlook that may cause this?
Or could there be another cause?
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abelenkiyConnect With a Mentor Commented:
Turn off cached exchange mode and see if it makes a difference.
Go into the account setup in outlook and uncheck the box.
thomcaAuthor Commented:
I will give that a try.  Why might that cause the problem, synching?
Yes, slow connection to server, or some other nonsense on the client pc.
Try to determine if it happens mostly with emails that have attachments, in which case it may be a virus scanner causing this.
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