Попробуй написать

UJ> document.all.HintObject.style.left = ParamObject.offsetWidth + S_OffsetLeft + 10;
UJ> document.all.HintObject.style.top = S_OffsetTop;

так

document.all.HintObject.style.left = (ParamObject.offsetWidth + S_OffsetLeft + 10) + 'px';
document.all.HintObject.style.top = S_OffsetTop + 'px';