No, of course you shouldn’t get flaky behaviour from compression apps or any apps for that matter, but, in my extensive experience, this behaviour is very much part of the ‘wonderful’ experience of running Windows.
Uninstalling an application in (either using the application uninstaller or Add/Remove programs) rarely uninstalls everything that was installed alongside it and it maybe this that starts to cause problems. I have numerous XP systems whos applications crash on exit or suffer from multiple general errors on shutting down, or I have to end various processes with the task manager. I’ve just got used to it.
Although no excuse, let’s not forget that Windows XP is getting on to be well over 7 years old.
The demo version of Procoder is very much out of date and I would base any purchase judgement as the lastest version is so much better.