Analysis Server appears to hang

We had an ongoing problem where by users would suddenly start complaining that the Analysis Server was hanging. When investigating the box we could see that there appeared to be no physical constraints. Disks were a bit above average, CPU was very low and there was plenty of memory.

When looking at the server through the SSAS activity viewer (part of the community samples) we could see that users were definitely queuing up and many of the queries should have returned in less than a second but were hanging around for ever (30 minutes or more). It was as if we were experiencing some form of blocking…….