Jnes is not a perfectly written piece of software, like most freeware and emulators it doesn't go through any type of quality tests or rigorous benchmarks on different of hardware. If you have problems, it's quite possible that your computer doesn't like Jnes. Solution? Either find an old version that use to work, and try to help me.. or use another emulator, there is plenty of good ones available, try NESten, loopyNES etc..
Insulting feedback will not be tolerated, you will be banned, there is no excuse. I'm locking this thread, use another one to contribute information to this topic.