Unreal Ed 3.0 Critical Error!

[Uncle_Bob]

Iam using Unreal ED 3.0 that came with UT2K4 DVD (1 disc) and I keep getting a critical error:

Build UT2004_Patch_[2004-05-10_17.18]

OS: Windows 98 4.90 (Build: 73010104)
CPU: AuthenticAMD PentiumPro-class processor @ 1002 MHz with 255MB RAM
Video: NVIDIA GeForce2 MX/MX 400 (5664)

CreateWindowEx failed: The operation completed successfully.

History: PerformCreateWindowEx <- WListBox::OpenWindow <- WProperties::OpenChildWindow <- WPageAlignment::RefreshPropertyWindow <- WPageAlignment::Refresh <- WPropertySheet::RefreshPages <- WEditorFrame::OnCommand <- WWindow::WndProc <- WWindow::StaticProc <- MessagePump <- MainLoop

This is the message I get. It happens when I try and minimise the texture browser. It wont let me and just stays there, I then get this error! Does any one know what is causing the problem and how to fix it!