See this thread from 2 years ago on using a batch file to maintain several copies of your hierarch.??? file.

http://community.pmail.com/forums/post/1093.aspx

All my filing trays disappeared.  Has anyone seen this behavior before?  Is there any way to recover the structure?

 I'm running PM 4.50 PB1 on XP, SP3.

 All my mail folders appear to be fine, they're just no longer organized.

 I can't be sure of the timing but the problem may be coincident with setting up an IMAP account in the same PM user account.

All my filing trays disappeared.  Has anyone seen this behavior before?  Is there any way to recover the structure?

Mmm.  Yeah, backup.

 Thanks for the guidance.