If you use the bootloader is offered on a different SD and keep your old 3.3 bootloader than it will be updated again at next start to your old bootloader.
So I suggest to delete or rename the old bootloader file to keep the 5.5128 ;)

old bootloader on original card only, 5.5128 on card with NC and maps, it only updated once, doesn't update again unless I put old original card in, I did notice though that after it does update there is a red line/box around the bootloader SO clist#30068 RVCT, does that mean anything?
am so close thanks to all your help, its just trying to work out whats causing problem

You ignore the red bit as it only indicates your TT does not like a bootloader that has an "illegal" version number.
Since internally it is the 5.5128 all is good.
So I guess Navcore and map are working now?

navcore and map and voices working, only problem that still remains is the screen/display alternating between what should be there and the shutdown screen with countdown (countdown gets to zero and shuts unit down after about 30 mins sometimes longer sometimes shorter) turn unit back on and same again.

Trying to pinpoint whats causing this problem is frustrating as its so close to being fully functional

could problem be card being a normal sd card and not an sdhc card? I have got a feeling the problem is something silly

Does the TT shut down during normal operation in the car?
Asking as every TT shuts down after a while when connected to your PC....

Downunder35m wrote:Asking as every TT shuts down after a while when connected to your PC....

Not every TT!!

this unit has to be plugged in in car as doesn't work otherwise (think battery useless) all time whilst operating in car it alternating between screens, when connected to pc it permanently shows connected to pc screen

Well, with faulty battery it is hard to say...
You might want to consider replacing the battery.
To me it sounds like there is more faulty than just the battery.

ok, heres what I tried
downloaded navcore_7.903.9183.go-go300-go500 from here via link navcore v8 thread, downloaded 905 map uk\irl to match navcore, downloaded zip, put all on 2gb card as per instructions, copied voices folder over from another download, used fastactivate to patch NC and activated maps etc, left bootloader as 5.5128. on unit.

turned on unit, waited short while, select language screen appeared, selected/confirmed then went through usual right/left hand etc, selected voice, then maps, then went to map screen, waited minute or so and satellite lock.

everything works as should, unit doesn't switch between whatever am on and shutdown.

tried NC 9.485 installer again but switches between whatever am on and shutdown.

so, the question is, what is in NC9.485 that could be causing, what seems like/appears to be a conflict?

its as if one piece of the software is telling unit/programme to do one thing and some other bit of software is telling unit/programme to do something else.

bit of a weird one, but am sure you guys on here can shed some light as to whats going on

The question what you installed using the installer.....
There are several users here that will confirm the installer works just fine on a 300/500.

hiya, well, heres the thing, started again from scratch, put maps etc and fast activate on card, then used installer to put on options for go models, put in unit got no maps useable warning, took card out, ran fast activate, put in unit and everything worked, ran installer again and chose memoryboost option and put on card but didn't delete anything and when put card into unit everything still worked, YIPEE
did same again on blank card but choosing memoryboost option and get alternating screen as mentioned before, erased card and did go models option then memoryboost option and everything worked

can you offer any explanation as to why? I not really worried but it may help anyone else who has a problem

thanks to you all for the help and getting me to think and try different thing, got there in the end

Not really, the MB option is meant for 32mb devices and creates a "swap" so unused parts of the Navcore are removed from memory.
Don't have access to a X10 for testing :(