When autobuild is enabled, M2M seems to do periodic rebuilds, even if you don’t change any files. This has 2 anoying side affects:
During a rebuild, a toolbar gets repeatedly added and removed if you have the target management perspective open. This means the the entire UI jumps about making it hard to see traces and shell outuput.
Even though nothing has changed, the dwl file still gets replaced. If you are downloading when this happens, the download fails, and you have to start again.
Also, if you are working through a list of compiler warnings, they dissapear, because the files weren’t included in the build, because they hadn’t changed. This forces you to do a clean build, and re-compile everything.
So that’s one incremental, and one complete build, when nothing should have been built in the first place! 
Agreed. I noticed the UI bug, but the download bug is quite annoying 
Hiya,
I’d noticed the download occassionally failing, but hadn’t worked out why. Thanks for pointing out what is going on.
I will also agree that the UI ‘flicker’ in the Target Management perspective is a right pain.
ciao, Dave
The most anoying thing about this ‘feature’ is that as discussed in this thread, files changed outside of M2M will not be included in the rebuild. This means that as the build was not triggered by changes to the files from within M2M, these rebuilds will never achieve anything!
So don’t do that, then! 8)