Recently I've done some work on automating the creation of our deployment packages. In this process I've used some tools on my Vista client to make sure things work before running live on the server. Like yesterday I used mt.exe to embed a manifest file into our exe files, which (after several runs) resulted in:

mt.exe is not a valid win32 application

What!? I looked up the file in Windows Explorer and saw that the file's size was 0KB! What is it that I do so wrong that I'm able to totally clear out everything in an exe file just by running it?

This has happened to me several times. Once with mt.exe, once with mage.exe and 2-3 times with Excel.exe (2007)! Excel was ok after log of - log on, but the other files I had to manually replace to get them to work.

After searching the net I found that many has this issue with Excel 2007, Access 2007, Snippting Tool and Windows Media Player after installing Vista SP1. I guess I can add mt.exe and mage.exe to the list...

Here's the post mentioned. The interesting part is this:

Microsoft is aware of this issue and is working on a fix. As several people have observed, this is konwn to affect Excel 2007, Access 2007, Snipping Tool, and Windows Media Player on Vista SP1.   The fix is to either exit as many apps as possible that you are running (e.g. Outlook), and then load the app (and then you can reload the apps you had running), or a logoff/logon will clear it up for a while (days/weeks).  The error messages are confusing, but the problem is neither an invalid application file nor insufficient system resources.  It only affects certain applications, and typically only after the user has been logged in for an extended period of time.

and then a response on 14th of May from a MS representative:

We're working on it, it's going through full testing right now and should be available in a few weeks if there are no issues found.

In the meantime: You don't need to reboot, just log off and log back on. It's a per-user issue. That will clear it up if it's the same issue.  I realize it can be a pain and I'm not trying to minimze the issue at all, but the workaround is simpler/quicker than a full reboot.

It hits different people in different time frames. It depends on how many apps you are running and how often you have loaded/unloaded them. 

I appologize that it takes this long, but we'd rather not give you an update that had other problems/regressions, so we want to make sure it's fully tested, and that can take a few weeks in an environment as complex as this, as I'm sure you know.  

This is all good, but now in mid June there's still no fix to be found. The mentioned workaround works for me with Excel, but not the other apps. Please let me know if you see a fix for this, and if you work for Microsoft and has any info about the issue please let me know.