After few installations of 3rd party SIP/T9, your autocomplete may not work correctly due to changes made by the software. ie. no contact pop-ups on click to: for sms or no dictionary pop-ups while normal writing.
before installing any new sip, take note or backup these reg keys/values;
hkcr\keyboard layout\preload\*
hklm\system\currentcontrolset\control\layouts\*
hklm\system\currentcontrolset\control\keyboard layout\*
More details abt this issue here
