Shimano Alivio, Think they are Square taper by looking at them. The bike is a Giant XTC 4.5, the cranks and BB were changed by Giant due to failure of the old ones (Truvativ Isoflow)

My mate thinks if I take the cranks off and lube them a bit it might help.

The bike has been sitting for a few days but was fine last night when out for a test ride