I don't know why but I thought sometimes you may have to install both VMS8 & DVDA and activate both of them.
Mine works with the files from an AVCHD created in a Sony Cam, no problem.
I did though do something to the cineform codec by installing some trial cineform programs & players.
After uninstalling VMS & DVDA I then went throught the registry & harddisk removing all entries to cineform & Sony etc. Re-installed & all working well.
If your that impatient you can download the trial version of Vegas 7.0e.
That program loaded my m2ts files from a sony avchd cam with no problem.
After I inserted them into the timeline I export them as xxxx.m2t (HDV Video files).
If Vegas Trial doesn't work your computer probably needs to be cleaned up (with a vacuum).