I am not sure what is happening in my bathroom. Please help me figure this out. After taking a warm shower we notice that there was drips of water coming from the cielings exhaust fan. Upon further inspection (removing the cover,removing the insulation from the attic where the fan is,noticing for any roof leaks) I came upon moving the venting hose attach to the unit,that there was drips coming out from the hose.This attachment is connected to alum. Pipe leading toa gable cover . There hasn't been any rain, but it has been extremely cold here for the last couble of days. Please help??

Your question title answers it. Water vapor from the shower is condensing in the fan housing and duct work. This is a problem you need to fix, but it may not be easy. Start by carefully insulating everything. You might even replace the aluminum pipe with PVC which is naturally less conductive. Shorten the route the duct takes if you can. You may need to replace the fan with a more powerful one to push the air out faster.