We had the same problem. Opened a PMR, and got an answer from IBM :
Thank you for the description you provided. From it, I was able to identify the issue in Lotus Notes SPR # RMON7M2JM9 “Brief Description:* “Notes IPC Asynch Message processor (1)” error in 8.0.2 STANDARD when opening mailfile”
This issue will not been adressed in 8.0.x. A programming error was found but will not be corrected. It will be a permanent restriction. In 8.5 it is not reproducible.
Workaround
Deleting the cache.ndk desktop6.ndk bookmark.nsf but the error will return few days later
In addition to what IBM has suggested, try the below as well. Have had a lot of users experiencing this issue and the following managed to stop the Notes IPC Asynch Message processor (1) error from re occurring.
(1) As IBM has suggested Delete the Cache.NDK, Desktop.NDK and bookmark.nsf
(2) Delete the workspace folder
(3) Open regedit and navigate to HKEY_CLASSES_ROOT.
Delete all the keys and all entries under the keys: HKEY_CLASSES_ROOT\Notes, HKEY_CLASSES_ROOT\Notes.Link,
HKEY_CLASSES_ROOT\Notes.NotesSession,
HKEY_CLASSES_ROOT\Notes.NotesUIWorkspace.
Close regedit
(4) Run the Lotus Notes 8 installation cd and select the option “Repair”.
What is the purpose of a developers forum if nobody responds? Please at least indicate if it is something you are looking at or if it is a user configuration problem. I have called the IBM help desk and they had me delete the cache.ndk and recycled Notes, but this error always returns.
I have the same problem. It occurs when I go into custom expiration by date. I just upgraded to Release 8.0.2 HHF206 thinking it would go away but it didn.t It’s suspicious that it happens related to the expiration folder. I think notes is expiring documents anyway even though the expiration date has been extended.