Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

an hour ago, after a normal restart, my PATH environment variable just disappeared.

It does not appear in the:

  • not in System Properties/advanced/environment variables.
  • nor under "User" and not under "System" variables
  • not in the registry HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment

Fortunately, I have backup of my env vars, so the only question is

WHY did it happen? (and not "how to repair it")


  • I'm on Windows XP, sp3.
  • before the incident I tried to install a new monitor, which didn't work
  • I had other custom variables that I created manually for my own needs, and all these variables remained intact. Only the PATH variable vanished!
  • all these variables (both PATH and my manually defined vars, where defined as System vars, not User vars
  • since there was no PATH var, the default PATH pointed to C:\Windows\system32. this rules out security attack of that sort, I guess. (or just proves the opposite?!)

edit : I ruled out gremlins, because it had happened before midnight && after 9PM

edit2: I ran 2 registry cleaners just 3 days ago (reg-mechanic and regSeeker). the first took tons of time to run. It's not magic fairies but it's pretty close ;)

edit3 - I did not touch or change my env variables lately, so it wasn't "by accident". besides, it happened twice already.

share|improve this question
I would suspect a boot sector virus of some sort. – Moab Sep 13 '11 at 23:34
Magical fairies? Act of god? Gremlins? Failed monitor install? What have you already done to try and determine 'why'? – Ƭᴇcʜιᴇ007 Sep 13 '11 at 23:38
had i known what to rule out, i would've done and write about it. suggestions (based on your advice i ruled out gremlins.) – Berry Tsakala Sep 14 '11 at 0:19
maybe you went to edit the path, highligted it, and accidentally clicked delete.. or you went to delete a variable near it, accidentally deleted path.. i've used xp for almost 10 years and not seen that. you could get a program to monitor the registry key there. – barlop Sep 15 '11 at 1:22
Did you install anything recently? Ive seen some program installers wipe out the path variable before. – Keltari Sep 17 '11 at 17:35
up vote 0 down vote accepted

it was probably due to misuse of setx.exe inside a vbs script.

when using setx.exe, always surround variable contents with double-quotes, e.g.

setx.exe varname "value of that var" -m

from vb variants:

cmd = "setx " + varName + " """ + Value + """ -m"
share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.