Hi Rowan. i just had a similar experience in the weekend. Here's what I did:
- Opened an old file (from Corona v1,7) - about 99mb uncompressed.
- Corona didn't show any warnings (regarding displacement etc.), so I manually reset the renderer to default settings, and then changes UHD to Path Tracing.
- Pressed "Render" and it rendered fine.
- Then I started IR and the system hang (frozen white window)
- After around 15 min I force closed Max.
After that I tried 2 times to open the file again and use IR times with the same result (frozen white window, with "not responding" message).
Can't give the file ATM, but here's some details: 3dsMax v2014, Corona v4, Windows 10 PRO, the file contained Laubwerk trees (updated to latest version), the scene was lit by an EXR.
Hope it helps to find the culprit :)
Regards