RTB Differences W2K vs. W98

My application which uses the Rich Text Box control works perfectly under W2K, but not W98. For one thing, horizontal scrolling doesn't work under W98. If you grab onto the scroll cursor and pull it to the right, the text doesn't move. When you let go of the cursor, it springs back to the far left. Another problem, I have a line of code that reads:

rtbReport.SelRTF = "To: " & CustomerInfo(Name) & vbCrLf

Works perfectly under W2K, but VB6 hangs when trying to excute the same line under W98. Anyone know of any references that indicate that MS's Rich Text Box control functions differently in the two OS's?