My 18 month old Lowrance HDS-5 kept freezing.
The problem started after I followed the instructions on the Lowrance site and updated the software, the update completed successfully and all appeared to be working ok. But when I zoomed in or out, the display froze, none of the buttons did anything, all I could do was remove the supply.
I emailed Navico at about 20:15 on a Friday 6th thinking they would see it first thing Monday, to my surprise I had an answer within 45 mins, telling me to send it to them. A brand new replacement arrived this morning.
Maybe something to do with the fact I had the email address of their Global and Uk Service Co-ordinator and dealt with him directly..