Hi
Under the VP Tools/ Option/Media settings you can set the default duration value for your still image clips and -Yes you have to set this before loading any images! Blast!
What you can do though, if you have already loaded the timeline and don't want to redo it is to...
Save your timeline contents as a Sequence.
First take off you music track.
Click the tab marked Sequence on the TOP toolbar and select "New Sequence"
This will clear the timeline and put your images into the sequence bin as a complete new copy clip. (It will be a videoclip)
Now open the Sequence bin which will now have 2 clips in it. (Sequence No2 is a dummy)
Load the Sequence file No 1 which will be your sequence of images in video clip form onto the timeline.
Re-add your music sound file.
As your images will not have altered their duration the sound track will not match it which was your original problem.
However If you now right click the timeline you can "Change Clip Speed" so its duration matches the sound track. You can calculate the % difference required...the higher the percentage the faster the clip will run. So you will have to experiment a bit possibly with both visuals and the sound, but you should be able to get them very close.
Don't try dragging the end of the video clip back as this will simply cut off the end image.
Nat