It looks like the boiler is needing some TLC courtesty of a trusted gas man, if there's such a thing....
I suspect there is a fair bit of limescale and other deposits inside the boiler, and it just can't disperse its heat quickly enough due to this. I can't really recommend anything for you to try now, unfortunately but I don't think your system is dangerous. It does need a professional opinion though, and get them to write down what they think the problem is...there's just too much bullsh1t flying about in this trade.
John, November 2009