Intermittent wiper problem

My Freelander 2005 1.8 Petrol has a problem with the front wipers.
All is ok, until i put them on intermittent, It seems to switch on in very short bursts, so stops where ever it wants, and when you switch them off, they just stay where they are.
Any ideas how to sort it?
Thankyou

don't use intermittent.....sorted

Yeh, thats what im doing at mo, thanks lol
Rather see if can be sorted first tho :0

Sorted, drilled out the rivets on the stop start switch thats attached to the motor, the 3 contacts inside were gunked up with grease, which was stopping 2 of the contacts connecting to the rotating plates,
Just cleaned them off well, tweeked up the contacts and lightly sanded them for a clean contact.
cleaned off the pld silicone and replaced the plate with new silicone, fixed in place with self tap screws.
Put everything back together, now works perfectly.