Does anyone know how low the memory on the Desire has to get before it tells you it is low on storage space?

Mine suddenly out of nowhere said it was low on memory, even though I haven't downloaded or updated any apps, cleared all my cache etc. It's saying I have 14mb free storage space, so surely this isn't "low"?

Confused.com!!

 

Cheers, found another thread on here which detailed clearing the data from apps etc and i've now got close to 30mb back!