Device Will Only Connect Once, Then Have To Reinstall iTunes Again

Hi, I've done a search and cannot find an answer.

On my laptop (win7) I have an iPhone4, Touch 4th gen and two shuffles.

They will be recognised once, the next time I try to connect them to iTunes they cannot be found, the only way I have found round this is to uninstall iTunes and put back on. They will then each conenct once and not again.

After I have synced them I eject them using the eject icon in iTunes, I have never just pulled the USB cable out so don't think there is anything I have done wrong.

When uninstalling I remove bonjour and the other apple apps too.

Help!