This could lead to security issues.
.com is a file extension for DOS executables. Someone could have created a malicious
.com file called "google.com" that somehow ended up on your hard drive, and when you do:
/run google.com, mIRC would execute the file, and the malicious executable google.com would run.
It can also conflict with another .com filename that exists on your hard drive.
Ex:
Let's say you want to visit
www.format.com , using you're way of doing:
/run format.com
would cause the '
format.com' program to run.