VSx5 - MP4 file format mismatch

[Taff in Exile]

Hi All,

I've got an annoying issue and I wondered if you lovely people would help me out.

The problem I have is I get a File format mismatch error message [16803:1:2] when trying to load some mp4 video clips into Video Studio pro X5 for editing.

The video clips are recorded on an Avermedia Live Gamer HD capture card in MP4 (h.264 + AAC).
I've played around and noticed that video clips below 4gb are load into VSx5 fine and I can happily edit the videos but any video clips over 4gb get the file format mismatch.
I can confirm there is nothing wrong the 4gb+ videos files as I've been able to edit them fine within Sony Vegas pro 12
Is there an issue where VSx5 cannot work on MP4 files above 4gb? are there any known workarounds or fixes? Previously I've been editing FRAP recording which are 80GB raw footage so I don't think its a system limitation but maybe a codec ??

System
CPU - AMD FX-4100
RAM - 16GB
HDD - 2TB
GFX - Nvidia GTX660 2GB
Windows 7 Home Premium

Any ideas would be great as I like the VSx5 interface more than Sony Vegas.