This is prolly not a mirc bug. It wasn't reported before (afaik), so it's prolly something at you. If you are using a script, unload all dlls and turn remote off (i don't think remote will be able to affect that).
Code:
//var %i = $dll(0) | while (%i) { .dll -u $dll(%i) | dec %i }

If after unloading all dlls this thing still happens, try using a fresh install of mirc, and not your script. If you are not using a script, and you are sure no dlls are loaded, then it might be a bug.