Hello kamah. Welcome to the Forum.
I took a look and found that the error message can be associated with at least 2 conditions:
- You have an old game or program installed that is incompatible with Windows 7.
- You have malware on your machine that has added unneeded .com files
Diagnostic for #1: The NTVDM CPU has encountered an illegal instruction. - Microsoft Answers
Diagnostic for #2: run a good antivirus/anti-malware scan.
See if that helps