I can't answer your question directly but I don't think any respondent will scroll through 400+ options in a drop-down. I would search this forum for "autocomplete " or look for another solution.
Cheers,
Tony Partner Solutions, code and workarounds presented in these forums are given without any warranty, implied or otherwise.
I'm trying to understand whether there is something wrong in my list... but it doesn't seems so..
I've tried to add a restrict number of rows until the error appears again... it seems that my dropdown accept at most 330 rows.. if I add 331 rows and try to "save" my list, the error appears again.
Very strange, isn't it ?