You don't mention which version of ImageGlass you are using.
I'd seen this (or a similar) problem in the past, and thought I fixed it. You might take a look at
Issue #360 in Github, and tell me if it looks like the same problem.
For me, I could cause the problem by the following steps:
1. Have a DVD mounted in drive D:
2. Run image glass, view some images
3. Eject the DVD (un-mount drive D:)
And on next time running ImageGlass, I'd get the "no disk" errors. A Windows reboot seemed to fix it, until next time.
I attempted an IG repair which should have been released in
IG 6.0.12.29 - if you're using that or the 7.0.7.26 release, then I probably need to revisit this issue.
Let us know ... Thanks!
P.S. - Oh yeah, try disabling the "check for update" setting in IG - Settings, General.