If you are having problems downloading files, it is most likely due to DCC ignore.
It is also best to make sure that you auto-accept files, because if you are downloading from bots, you only have a certain amount of time to accept a transfer, if the time passes, then you have wasted all that queuing time.
Click Tools - Options and click the little + beside DCC in the menu on the left. Make sure DCC is selected. Now change On send request to auto-get file and If file exists to Resume.
Now in the menu on the left, click Ignore which is under DCC. Change Method to Disabled, and also untick the option "Turn ignore back on in:".
This should help, bye bye.
PS, this should only work on mIRC.