Try renaming the configuration, then installing the extensions one at a time.
Locate the configuration folder that contains the winFileCache ***.dat file and rename it.
Open DW to recreate it and then close DW.
Open the extension manager and remove each extension, then install Data Bridge, open DW to start the WebAssist installer to finish the install for Data Bridge.
restart DW to test the Data Bridge functionality. Close it, and repeat to install Design Extender. then eCart, then free tools, and then MySQLi.