Declan,
A quick search for "could not parse the file" on the Cow forums turns up some nearly identical threads - all of which point to the file being CMYK instead of RGB. I know you said you converted it but...
http://forums.creativecow.net/search.php?q=could+not+parse+the+file&f[]=2
If that doesn't help then please provide some information about the file you are trying to import.
-E