In Mio S series you also have to change appstartupsec.ini, but the file is located in \My Flash Disk\Program Files\Navman directory. You need to change:
[Process1]
RelativePath=TRUE
ProcessFile=SmartST_CE.exe
DefaultCmdLine=
BootCmdLine=
StartOnBoot=1
MaxRestarts=3
TreatCloseAsError=TRUE
Major=TRUE
WindowName=SmartST_CE
MaxCloseMessages=10
KeysToForward=0x7A,0xC4
KeysToBoot=
to
[Process1]
RelativePath=TRUE
ProcessFile=\\..\\My Flash Disk\\Primo\\Primo.exe
DefaultCmdLine=
BootCmdLine=
StartOnBoot=1
MaxRestarts=3
TreatCloseAsError=TRUE
Major=TRUE
WindowName=SmartST_CE
MaxCloseMessages=10
KeysToForward=0x7A,0xC4
KeysToBoot=
and save!
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