According to this thread on the Codemasters forum, the 360 version of Race Driver GRID is showing some technical hitches for some users, namely freezing.
Dev head Gavin Raeburn has admitted there’s an issue and has promised a patch in the near future.
“We’re close to getting to the root of the problem and we will be including a fix and a backup workaround option (just in case) in our forthcoming patch due within the next few weeks or sooner,” he said. “We think the issue is due to specific drive hardware, possibly with bad blocks/sectors.
“The best temporary measure is to copy your gamertag to a mem card, remove the hard drive and run the game that way. Replays and caching will be disabled, though instant replay will still work as this caches to memory.
“I hope this helps in the short term.”