Description of problem:
Shorter version - the business-central process instances perspective can show an instance both as active and as completed at the same time. Trying to abort such an instance fails with "Could not find process instance for id <id>"

Longer version:
You can create a process with a timer node that has an invalid duration defined. It is possible to run an instance of this process from the business-central. The timer node is immediately passed as if nothing is wrong. In the database, in processinstancelog table, there is both a record of this instance as active and as completed.
This results in this instance shown in the business-central as both active and completed, since that is where the information about process instances is taken from for the gui. Unfortunately, if you try to abort this instance, you get an ugly stacktrace about "Could not find process instance for id <id>" - since that instance is not active any longer and is not therefore in the processinstanceinfo table.

The process to reproduce this is attached. Tested on PostgreSQL 9.1.

Version-Release number of selected component (if applicable):
BPMS 6.0 ER2