I work on WinXP, Office 2003, OE6
when closing the Outlook Express a pop window appears which propose to compact the messages in OE
how can I get rid of this annoying pop
please advise
thanks

It is a default function of OE.

You can do it manually as well:

http://www.insideoe.com/files/maintain.htm

Also:

Changes after installing Service Pack 2
The backgound compaction feature is removed from OE after you install WindowsXP Service Pack 2. Instead of compacting in the background, which was often the source of problems, OE now waits until you open and close the program 100 times. After that 100th time OE begins to compact. Do NOT stop this process! Do NOT turn off your computer or put it into Standby (Sleep) mode! Do NOT use your computer until the process if complete! Doing any of these things can cause the compaction process to fail and result in lost messages