I restarted my PC and then Avast Behavior Shield was turned off. Then Java update popped up and I put it to install. Went to have lunch and came back to a message that Avast had blocked MSI78B1.TMP in C:\WINDOWS\INSTALLER folder and Java had finished updating.
Why was Behavior Shield turned off after reboot and what was the installer that it blocked? Last thing I installed was M3DataRecovery to try to recover my SD Card with no success so I uninstalled it before the reboot.
The Behavior Shield turning off is a known problem which Avast will, we hope, fix.
You could try to start it manually, or reboot (again).
MSI78B1.TMP would appear to be a temporary file used by the installer, and if you view it you might see something that would indicate what program it is related to. It is possible that it was the Java update, and that it installed despite Avast blocking the file. You could check the version of Java to make sure you really have the latest version.
Before I left my PC there was a LZMA_EXE process in thr task manager with no extension - just filename. When googling it the first suggested search was something to do with java. So I think it was a Java installer problem.