I have a Sony Vaio VGN-FW235J whose battery is now deemed incompatible with the computer after almost a year of use. A call to Sony that resulted in me downloading new drivers, turning off the computer and unplugging it, then holding down the start button for a three minutes when rebooting (supposedly to discharge static electricity on the MOBO). That worked for about an hour.
When the box pops up notifying you of the incompatibility, the computer wont allow you to anything but close some windows and then power off.
I have asked Sony for a replacement battery since I have a three-year extended warranty. I haven't gotten one. I did my own tests on the battery and found one cell down in voltage output compared to the others, but I can't find documentation as to what the cell voltages should be.
So, I use the Vaio on AC power only and hope that it won't come unplugged by someone tripping over the power cord. The battery sits on a table since it can't be installed in the computer as it will cause the error message to show and lock out any subsequent work.
I recently have met other people with various Vaio laptop models and every one has a battery problem, usually related to very short battery lives with less than 30 minutes being typical. One person also has the same model as do I and has the same problem with the same solution - using the computer only on AC power.
Sort of dents the reason to own a Sony Vaio laptop.