Error occur on it says MeshPacket 12 does not exist.
It’s hard to determine what could be the cause of the error you are getting since you did not include in your post the list of the applications you just installed. And you did not indicate what operating system you are using.
But anyway, since an error already occurred after a few installations that you did, you may try checking your computer for any possible errors it might have.
Use a disk utility application to check your system. If you don’t have one installed on your computer, you may use Windows’ disk check tool.
For a much thorough diagnostics on your system, use disk utility applications like Norton Utilities, PC Tools Performance Toolkit, or Norton SystemWorks instead of using Windows disk check.
If checking your computer did not solve the problem, try to uninstall then reinstalling those applications one at a time.