Outlook won't send or receive emails

Outlook 2010 - I recently had to use my Toshiba restore disk to restore the computer to it's original state. I backed up my pst file and used it for the new install. No problems, all my data was there Outlook worked as it should in every way. Now (1 day later) Outlook will not send or receive email, all of the data is there and all other Outlook functions still appear to be normal. I get the following error message when attempting a send/receive: Task 'bobnewman@cox.net - Sending' reported error (0x8004010F): 'Outlook data file cannot be accessed.' (I get the same error message for receiving). Outlook has the correct location of the data file listed. If I make a new appointment, stop & restart Outlook the appointment is still there so at least in that case Outlook appears to be accessing the pst file okay.

Can anyone help me please? Thanks, Bob

NOTE: Because the restore disk gave me Windows as it was 1 year ago Microsoft has been sending many updates to bring it current. I don't know if this is a coincidence or not but it was after one such update this problem started occurring. HELP, HELP, HELP!

Thanks in advance... Bob