Works fine, but you might wanna consider adding what Jess Rahl said to the script. :)

for the problem with the button size, just change the 7 at the END of these:

button "Yes", 5, 7 91 50 7, close
button "No", 10, 115 90 50 7, close

to something between 10 or 15. i found 15 to be too big, so i went with 12.

i had a problem like Pariah had. it kept flooding my status window saying: * /dialog: \'Query\' name in use (line 27, Query Blocker)

I don\'t really see how this helps. Maybe if it had a friends list that if a nick/address was added to the list the pm would automatically open instead of having to accept every PM you get. Also you get an error message if the window is already open when you get a PM, so if 2 people PM you within say 1 second, you get an error message and the PM query window is closed without you knowing someone tried to PM you. The initial message is not displayed in the Query window when you accept and as mentioned by byzaNce760, the buttons are too small. 3/10

Works good for me, but is there any way to change the size of the \"yes\" and \"no\" buttons? They\'re kind of cut off, and it\'s just a small annoyance. :P

Excellently designed, though the text is rather small/blurry

A big improvement, I think, would be maybe a timed query only ignore after denying a query...this way users couldn\'t spam you with popup windows by rapidly querying you; you just deny it once and there you go.
Another thing is I would try to use $input rather than a dialog in this case. You don\'t have to, but if you decide not to then consider a dynamic name for the dialog (so the dialog open command would look like /dialog $+(query.,%qnum) query) so that you can have multiple dialogs open at the same time. The problem with what you have now is that if Person A queries you and while you are deciding whether to accept or decline, Person B queries you, you\'ll get some errors since it tries to open up another dialog named query, but it can\'t since there\'s already one open.

Well, as I say I only tested it once.
After I saw that manpreet scored it a 10 (and I changed my underwear).
I connected 2 clones, and messaged myself, and all hell broke loose. Lot\'s of errors in the status window (* /dialog: \'Query\' name in use (line 27, script8.mrc)) and the dialog would continue to pop up after saying no.
It needs alot of work... you should rethink how it should function, and account for ways that it can be broken.

I accepted a query and it echoed something in my status. Like \"-x unknown command\" and a few others or something. And it closed my query.

Why. What happen?

Did you even test this?
I tested it once and it broke...

Works Great :D