Video from still cameras can cause these kinds of issues in Premiere Elements.
The best solution is to convert the video to DV-AVIs with Windows Moviemaker before bringing it into Premiere Elements.
To convert a video into a DV-AVI with MovieMaker, simply import it into MovieMaker and drag it to the MovieMaker timeline. Then:
From the Main Menu select File/Save Movie File
A dialog will open - Select ‘My Computer’ and press the Next button.
On the next screen you can name the new file and select/browse to a folder to put the file in (remember where you put it because you will need to browse to the file in Premiere Elements to import to you project). When you have named the file and selected the location press the Next button.
Is there any other method, as I've got quite a few I need to edit together? i.e. some online service to convert for me??
For file format conversion, I use DigitalMedia Converter to do batch file conversions. It handles both the Audio and Video and outputs to DV-AVI Type II files with PCM/WAV 48KHz 16-bit Audio. I'll load it up, point it to an output folder, get a cup of coffee and when I get back, all is done. It is shareware, not freeware, but has worked perfectly for years and many thousands of files, of all sorts of CODEC's. Note that it requires that any necessary CODEC's be installed on the system, as it does not ship with any of its own, which is a good thing in my book. Some converters will add their own CODEC's, and a few will overwrite properly installed CODEC's with versions that are not the ultimate. I like the fact that it works well with all players and other utilities, that I have, so I do not need to install alternatives, or remove anything else, that works on my system. I have used DMC so much, that I have a copy of it on every one of my computers.
Also, check your camera to see if you can set the bit-depth to 16-bit, and the rate to at least 22KHz, for the Audio. Many cameras allow you to adjust this, and that might get your files (for next time) into spec. If you cannot change this setting, then conversion will be your only choice.