If you can send but not receive files

Could it be your DCC is blocked by the DCC Ignore function?

In the File/Options/DCC/Folders menu you can set mIRC to save certain file types in certain directories and/or to ignore certain file types. By default mIRC will ignore all files exept the file types that are considered safe, like *.bmp, *.gif, *.jpg, *.log, *.mid, *.png, *.wav, *.txt, *.zip.

As you see mIRC will IGNORE executables and all sorts of script files by default. This safeguards you against the ignorant acceptance of virusses and other harmfull files. If you want to be able to accept other files by DCC, like *.exe, *.com or *.vbs files you have to add these to the list of accepted file types. When a file is offered to you and automatically rejected by the DCC Ignore a message like "DCC Send from domino rejected (Defrag.exe, file type ignored)" will show in the STATUS window.

Could it be your DCC is blocked by the LOCK option?

In the File/Options/General/Lock/ menu you can disable certain mIRC features and LOCK them with a password. This way you can block the DCC funtion, limit the channels mIRC can join to a small set, and disable the /run and /dll commands. When the DCC is LOCKed you will see a message like "DCC Send locked in options dialog" will show in the STATUS window.

Could it be the sender has wrong IP Address settings?

In almost all cases of DCC problems the initiating (sending) party causes the troubles. In almost all cases where DCC Send (or Chat) stops functioning (suddenly) or never worked at all, this is caused by wrong Local Host and/or IP Address settings at the senders side. Typically if the senders IP Address is not correctly set, the recieving party will get the dcc offer and try to confirm and connect to the -incorrect- IP Address. Of course, this doesn't work and you both sit there waiting. The sender will see the "Waiting for acknowledgement..." forever while the recieving person -did- acknowledge correctly. Here the sender has a wrong setup, not the recieving person. This problem is normally very simple to solve by setting the correct IP Address.