I have a bug with the intermediates tyres. When I start a race and the teams choose them all the cars have Bridgestone tyres, so Williams Benetton Jaguar Minardi and Prost instead of Michelin have Bridgestone. I have the 4.30a gpxpatch
Can you take a screenshot of the problem you are experiencing? It will most probably help others to understand whats going wrong and be able to give you a solution.
5 x WCC - S5, S6, S7, S8, S10 | 4 x WDC - S5 Nick van der Voort ; S6, S7, S8 Ed Greenhalgh | 2 x WTC - S6 Stuart Ingers; S8 Andrei Sevastian