I tested it on latest WinUAE 4.9.0 Beta19 QS A4000 040 128MB Ram! (no problem at all)
And my PC is slower: E5450@3GHz, 4GB Ram DDR2, Win10, all drivers updated. (pretty old for todays standard)
I guess something with your A4000 040 config must not be right!
EDIT:
And
here you can update all your Visual C++ versions to the latest!