I've used Valium on a couple of cats, for behavior problems, but I didn't see coordination problems quite to the degree you are seeing them. There was a general floppiness, sleepiness and a great increase in affection, that's what I remember. Valium loses its punch quite quickly, so Pouncer's reaction to it will diminish somewhat over the next week probably. In your place, I would continue with what the vet advised even though you find it hard to watch - it is working in the way it's supposed to and that's the main thing. Can he be confined to decrease the chance that he will hurt himself? I was unable to continue treatment with Buspar on one cat because I couldn't stand to watch him become like a vegetable, so I know how very hard it is to watch the extreme change in behavior. These things always happen on a weekend, don't they, when you can't call your regular vet and ask questions - sigh! If you call an emergency vet place, they will usually advise you over the phone if you are concerned about an extreme drug reaction.