Hi J_M,
This problem occurs on OS level when tries to launch vugen.exe to the memory. I don't sure what was the reason for VuGen crash and what was the damage of this crash last time but I would suggest you to following actions:
1. Delete local user configurations located under "<User>\AppData\Roaming\Hewlett-Packard\LoadRunner" folder.
2. Contact our support and provide them your log file (HP.LR.VuGen.log) located under "<User>\AppData\Local\Temp" folder.
Best Regards,
Yuriy