I was trying to install some software last week and I got an NSIS error. The message certainly suggests corrupt downloads, but corrupt downloads are relatively rare, and when they happen, redownloading it ought to clear that up. Getting two of these failures in a row with different programs is really a freak occurrence, so I started looking for another problem.
The most common cause of this problem is a pending reboot. If you didn’t reboot soon after the last Tuesday of the month, this should be your prime suspect. Try rebooting and then rerun your installer.
If you still have problems, try emptying your temp directory. Click start, then type %temp% and hit enter. Delete anything there that’s more than a few weeks old. A lot of programs don’t clean up after themselves in that directory, and over time, I’ve seen that cause a lot of weird problems. If you’ve redirected your temp files off your C drive, this is probably the first thing you should check.
If you haven’t moved your temp files off your C drive, check for low space on your C: drive. Here’s a nifty trick with Disk Cleanup to remove old Windows Update files, and a way to enable more aggressive compression.
Last and least, try re-running the executable from the command line using the /NCRC switch. Run cmd.exe, then do something like the following. Replace the path and filename with what you’re trying to run, of course.
Skipping corruption checks is bad form. A corrupted download could mean the file has contents in it that won’t run. It can also mean it has malware injected into it, which you don’t want. Although a lot of people recommend this, it should only be a last resort.
Chances are if your installers are failing to run, there’s something else that’s wrong. You need to fix that underlying problem first. Even if you use the /NCRC switch, that problem could still cause the installer to malfunction later in the process. And then you still have a problem.
That’s how you fix the NSIS error. Try the first three fixes first.