The Navman platinum range have had several firmware updates to fix various problems. The latest updates have pretty well solved all the issues that I have come across. Make sure you have the update which makes the transition of pages and touch screen useability drastically better.
Navman had my S300T for 4 weeks to bring it up to date as at end May 2009. Now it restarts about 4 times an hour. I do believe that the S300T is the worst piece of technology I have ever owned.
Navman S300T
