Any help would be appreciated.
Typically, Exchange automatically deletes these files from the %SYSTEMROOT%\TEMP folder once they have been committed to the database. Exchange's database engine also keeps a small number of these files open for each database. The files are deleted when a database is cleanly shut down, when a storage group is dismounted and when the Information Store service is stopped. If the store does not shut down cleanly, files that were open at the time of the dirty shutdown will remain.
For more information on this issue, as well as Microsoft's recommended resolution, see Microsoft Knowledge Base article 328583 entitled Lb*.tmp Files Are Created in the TEMP Folder and Are Not Deleted.
This was first published in August 2003