SilkTest 2010 R2 Class mapping on Win7 deletes previous mapping entries.

For Eg., Initially I have done a mapping "3030:ToolBar = ToolBar", saved it and closed the dialog. When i try to add an another entry i don't see first entry and if i continue to add second one and complete the process, initially added class map entry deletes.

Any one came across this issue and have any resolution.

OS: Win 7 (There is no problem on XP)
Version: 2010 R2