I've had loads of issues importing old PST files and our mail store on an SBS2003 box including the error in this thread. I've been importing by year in reverse order so older emails are in the older archives. I think this should be automated but that's a feature request. Importing emails by year into appropriately named databases would be nice but it's only available as a rollover option for new emails not importing old emails.
All my problems were due to the AutoGrow setting in SQL Server. I had this set too high at 1GB with 10GB rollovers and always around about the time of rollover, OMI would crash, this error would be logged and the SQL Server Event ID 17055 AutoGrow time out or cancel event would be logged.
Changing AutoGrow to 10MB caused further problems as the database would automagically change itself back to grow by 10% which would cause all the errors and OMI to hang and the server to become quite unresponsive. Auto grow by huge amounts like 1GB or 10% of 10GB causes numerous archiving failures, 17055 time out errors and OMI crashes.
I have this set to 100MB and everything seems to be happy. The installation manual recommends 20MB.
Edited to correct installation manual auto grow recommended value.