I've been in the industry for 18 years and it seems that during a Windows software install I rarely have problems with the install if I follow the instructions to 'wait while the software installs'. If I try to perform tasks (even ones that I wouldn't expect to be related or coupled with the software I'm installing), it seems that I'm more likely to have problems with the install - mainly for complex software installs like SQL server or IIS (in comparison with when I install this software and don't perform other tasks).
Does anyone have any data or references to any formal test results or studies that indicate the fault level from attempting to perform given tasks during software installation on Windows (or the comparative success level when not performing any other tasks, compared to performing tasks during the install?). I'd like to know definitively if there is any advantage to waiting for software to install as opposed to continuing with tasks.
Any comments giving advice on this, with some indication of the evidence/experience (including extent of the experience) on which comments are based would also be useful.
You are more likely to cause an object locking issue (file, reg key, whatever) if you mess about while the installer is running. Sometimes, the installer will be smart enough to offer to complete on next reboot, sometimes it will just fail.
I can't really give specific examples (other than countless failed installations I've suffered due to my impatience). I think this is easy to test for yourself. Build a simple installer that requires a specific file to be changed, then lock it and see what happens.
Another potential issue is if you change a regkey or file which the installer has already changed, and wants to come back and change it some more later. You will have left it in a state that is inconsistent from the perspective of the installer, which might also cause it to fail or leave you with an unexpected configuration.
So is it safe to do other tasks (against advise) when an installer is running? Only if you are not going to get in the installers way.