Goto “Control Panel” => “Add Hardware”
Select “Yes, I have already connected the hardware”
Click “Next”
Select “Add New Hardware Device” (at the bottom of the list)
Click “Next”
Select “Install the hardware that i manually select from a list (Advanced)”
Click “Next”
Select “Ports (COM & LPT)
Click “Next”
Select “(Standard port types)” – In left side
Select “Communications Port” – in right side
Click “Next”
Click “Next”
Click “Finish”

You should now be able to reboot and the CAPI_Worker module should no longer crash on startup. This guide solved my problem with my old Sony Ericsson W810i and the Sony Ericsson Suite. I used Windows XP on the Parallels environment so that I could upgrade the firmware of my cellphone.
The original discussion thread can be found here.