Calulator not working with snow leopard??

I thought I had checked most of the software I use for compatability with Snow leopard when upgrading from leopard with n know issues that I culdn't handle.
I upgraded yesterday with no probs but this morning I went to used the calculator app ( ie not the widget) and it came up instantly and told me it wouldn't work with the version??? Whats that all about - a built in OS app and it doesn't work????

I was just beginning to tear my hair out with frustration when writing this to get some help and the penny dropped - chuck the dock icon away, check applications folder and hey presto calulator - launched it no probs
So save that to the dock and bob's your uncle!

So thought I'd post this anyway just incase anybody else had a similar issue - most people probably worked it out already but maybe this will help some newbies