Help 3G/H data connection problem

I've got a problem on my HTC desire running stock Froyo and it's driving me nuts. As long as I'm not using the connection it reads 3G (sometimes H), when I want to do anything it tries to connect over 3G with no result, switches to H and starts working. It can take up to a couple of seconds. Lately it has even been doing it during downloads, causing downloads to pause in market and pages in browser to simply just not load. Google Maps has been going crazy because of this a couple of times as well. This is actually the first post mentioning something similar as to what I'm having...
I'm a T-mobile user in the Netherlands, maybe that has something to do with it? I know they are having some trouble with networks/upgrading lately