Just to add a bit to Pete's description of the problem -- I'm his "cohort" in crime... We had two VB.NET programs running on this particular machine. They suddnly stopped working with the indicated error messages. Nothing new was done to the programs or to the machine: no updates of the programs, no change to .Net, etc. The program's die on the following line, which they have in common. Dim sw As IO.StreamWriter = IO.File.CreateText(str_FileName) We tried reinstalling the programs using the install CD (.msi files, etc.). The installs were OK, but the same errors happen. It appears that something to do with StreamWriter or Scrippting in general has disapeared from the machine. We tried to copy the programs from another machine via Laplink: same error. We copied the entire subdirectory including the VB project and the installation project, etc. The copied folder on this machine had a dll missing from the Detected Dependencies. Why the dependency was lost is also a puzzle. Everything should have been identical in the copy folder as in the original. Don't know why not. This does seem to be a case where something got clobbered by, perhaps, cosmic rays, which changed something on the hard drive so the required dll is missing. We tried to find the "missing" .dll and then (re)register it. But there is no dll with the exact name shown. That is, we can't find a "bad" entry for the CLSID in the registry. And can't figure out which dll corresponds to the CLSID. We tried using Visual Studio Repair from Add/Remove Programs. We tried reinstalling XP SE. So at this point, we are fully frustrated. Is it time for Remove Visual Studio, Fully reinstall VS? All suggestions welcome. -- modified at 21:30 Tuesday 27th February, 2007 Charles Wolfe C. Wolfe Software Engineering