Recently, I am unable to delete most (95%) Outlook Express messages. Clicking the delete button doesn't work nor does dragging the message to the deleted message folder. This problem developed when I was having some problems with internet connectivity.

The problem could very well do with the bad connectivity cause if the emails were not fully downloaded they could very well be corrupt, and if this is the case, you would have to find the file where the emails are stored (srry, cannot help you there) you can delete that and start from scratch. That is all I think the problem is, and if I come across another idea, I would be glad to tell you.