Have you tried running the program in compatibility mode for Win XP or 98? This program is incompatible with 64-bit OS's, but this is the first time I've seen someone have trouble with it on the 32-bit version of Vista.
We do not recommend changing the DEP settings (Data Execution Prevention) because your system constantly monitors the programs running on our system and protects it from viruses and other security threats. If a security threat is found, it closes that program if they pose a threat.
If you choose to protect all programs, you can still turn off DEP for individual programs. If you suspect that a program does not run correctly when DEP is turned on, check for a DEP-compatible version of the program or an update from the software publisher before you change any DEP settings.
Listed below is a link to a forum discussion regarding similar issues with Vcast.