TomTom had removed the 5.42 update from their website and put the previous version back online again instead. This was done after noticing that a lot of people were experiencing problems with the update. TomTom support was literally swamped with complaints yesterday, and it soon became apparant that the only right decision would be to pull the update back from the site, which they then promptly did.
Update
The complaints were severe enough for TomTom for pull the update from their servers. However, after a quick investigation, TomTom has decided to put the firmware update back online. This is their official statement regarding the issue:
Update 5.42 will go back online – concerning the freeze issues: we have tested the freeze issues and could not reproduce them – when customers experience this we will ask them to ship their GO to us. Concerning the Traffic issues: the cause of this was a server issue that has been resolved by now.
You can download firmware 5.42 again here.