Try here:
http://www.sonyericsson.com/spg.jsp?...21839&esi=true
I updated my K750i the other day using their update service software & the standard USB cable
If you want to check what firmware version you currently have on your phone, do this:
Move joystick right, let go
Press the * (star key) once
Move joystick left twice
Press *
Move joystick left, let go
press *
This will take you to the "Service" menu.
Select "Service info" (should be first option)
This will take you to the "Service info" menu
Select "Software info" (should be second option)
The first line contains the version number. Will say something like "R1AA008" or R1AA005" or "R1N035" or similar
If you then do a google search on "R1N035" or whatever your current firmware version is, then you might find some info on other people who have had the problems you have experienced, and how they have cured them
Personally I would just try the update software anyway, if your phone is a very old batch, it probably has very old firmware, so updating it can only make your phone better!