Hi Patrice, it seems that there is no full solution to this issue at present. The problem is with a memory leak in Dreamweaver itself which of course is outside the influence of WebAssist. Until Adobe fix this issue, we will just have to cope the best we can. A workaround suggested by Jason was (I have edited slightly for clarity):
To start Data Bridge, set up the options you need on the Page Settings tab, go to the Manage Pages tab, add the Search page and configure the search page, then click finish and save a preset and create the search page.
After the wizard has completed, delete the created page, start the Data Assist again, select the preset you just created, go to the Manage Pages tab and add the results page. then click finish and save the same preset again.
After the wizard has completed again, delete the created search and results pages, then launch the wizard again, this time add the Insert page. Rinse and repeat to add the update page until you have all the needed pages added to the preset.
It actually doesn't add that much time to the process of adding your pages and it certainly worked for me.
I have been wracking my brain as to some way of putting pressure on Adobe to fix this issue so if anyone has any suggestions please leave a message here.