Few times, IE DLLs may get corrupt due to silktest or some other thrid party tools. By this, silktest may not able to get browser objects properly. To repair IE,

Re-Install
Start > Run rundll32 setupwbv.dll,IE6Maintenance "C:\Program Files\Internet Explorer\Setup\SETUP.EXE" /g
or
Start > Run rundll32.exe setupapi,InstallHinfSection DefaultInstall 132 C:\windows\inf\ie.inf

and select to repair IE if this does not help.... then another possibility would be to run the LSP fix in Internet Explorer
http://inetexplorer.mvps.org/data/lsp_fix.htm

Re-Register DLLs
Another way is, copy below info into a batch file and run it.
REM Ie6_cure.bat
regsvr32 Shdocvw.dll
regsvr32 Shell32.dll
regsvr32 Oleaut32.dll
regsvr32 Actxprxy.dll
regsvr32 Mshtml.dll
regsvr32 Urlmon.dll