itunes collapses during communication with itunes match

Hi there,

i´ve got a problem with itunes match. Every time i start itunes an error message appears that an error within itunes occured. This happened the last two weeks. Now itunes closes by itself without a warning. Only if i stop the communication with itunes match i´m able to use itunes. I´ve got a lot of songs. More then 20.000. Could it be that my account is over limit? What can i do?

I´m using the last version. No firewall in WIN8/64 activated.

Help would be appreciated. Thanks in advance,

Mo