Video Engine has stopped working

Hello, I’m working on a TV commercial and wanted to bounce a demo for my producer. Tried to replace audio in video but as soon as it starts merging I get this message “Video Engine has stopped working”. No idea what’s up never had any problems or major changes to my system.

Cubase doesn’t crash but the video shuts off. I need to send this demo asap. Please help!

Problem signature:
Problem Event Name: APPCRASH
Application Name: VideoEngineDecoder.exe
Application Version:
Application Timestamp: 4ed612e0
Fault Module Name: StackHash_0a9e
Fault Module Version:
Fault Module Timestamp: 00000000
Exception Code: c0000005
Exception Offset: 0bb17cf0
OS Version: 6.1.7601.
Locale ID: 1033
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

Windows 7, Cubase 6.5