That's because filepath is there. If you have the file (reglist.txt) in your mIRC directory have that as:
on *:TEXT:!to*:#: {
if ($read(reglist.txt,nw,$nick))
msg $chan timing out $$2 for $$3 seconds
msg $chan .timeout $$2 $$3
}
Otherwise, change the if statement to:
if ($read(C:\Users\(me)\Desktop\reglist.txt,nw,$nick))
As Nillen said it's down to preference, I never type in the long file name. It just looks hideous.