Wii says "memory full"

I think i know the answer, but just want confirmation, I modded a friends Wii and recently it told him that "insuffiicient memory" was available when he went to save a game, just wondering what could cause this. Could it be because there is too many high scores/game progress files on it already, or could it be something that happened in the modding process? what is the solution to this as the Wii is in Donegal and I am in Dublin.
Could the solution be to move some of these files to the SD card to free up some space.
Iwill get the exact wording of the error if that helps.

cheers guys

Wheelo,tell him to go to channels and see if there is a channel there for internet and connections,it will be a white background with grey to black writing,it will be around 1600 blocks,tell him to delete it and all should be well again

cheers sinno, if memory serves me right, it does have the internet channel, 1600 blocks is a very big channel, consider it gone

For some reason when updated it appears