Deleting the _fwsession.dbf, .fpt and .cdx files is a reasonable remedy.  The table _fwsession contains session variable data stored during previous requests.  Records holding expired sessions get re-used, but as whenever session variables get changed during a request, they update a memo field, causing the associated .fxp to grow in size.  Space in memo files can only be reclaimed by packing, which FoxWeb attempts to do upon startup.  Of course if the FoxWeb service does not get restarted very often and if you are running a busy site with lots of session variable updates, the .fxp file can get really big.  You can try to pack the file while FoxWeb is running, but this can prove difficult if channels are constantly keeping the file locked.

 

Another problem is that when VFP processes hang, or crash, they can cause corruption to open tables.  The _fwsession table is open during request execution and it is possible for this table to get corrupted if the channel crashes.