For my job I've been working on a large excel - based reporting system, being used by a lot of people in the company. There are a lot of macro's behind it and recently I encountered a problem I don't seem to be able to solve myself. I am hoping someone on this site could help me with it.

The problem is the following:

The reporting system consists of an excelfile with several sheets. There is visual basic code behind the sheets, as well as code in 9 modules. The code and the sheets have been tested and works. Sometimes, however, some of the macros behind the worksheets stop working (without an error coming up). For example: I've programmed that the excelfile cannot be closed by clicking on the x, but this suddenly is possible. Also: I coded that on doubleclicking a range of cells, the cells receive a specific color, but in this case just a cursor appears. My question is the following:

Does anybody of you already dealt with a similar problem? What could the reason for this problem be? Is there a fault somewhere in my code and how could I find it? When one of my colleague encountered the problem I went to have a look and opened the VB - editor, but no fault was marked or seen. The only solution to the problem was to close ALL excel - sheets on this computer (often they use several instances of my program at once: they all stop working at once also) and start them back up: then everything works properly again.

I've tried re-evaluating the code, used a code cleaner, ... and I'm getting out of ideas: is there anyone with an idea how to solve this?

Thanks in advance