Incorrect data displayed from web app & SQL – Dev says low bandwidth

Scenario:

Web-based CMS is displaying random data in incorrect places (Information entered in one area is appearing in other areas). Web app is HTML5 intensive with SQL2005 on back end. Site has DSL connection and IE8.

Dev explaination:

Minimum requirements of the web app is 512k upload. DSL test was reporting at 336k. Due to the high latency, data may have been crossed over if multiple clients were attempting to save data at the same time.

My thoughts are otherwise, but i am seeking consensus as to elmiinate bandwidth as the issue. Any technical explainations are quite welcome, as i’d like to send back to the dev and team.

Thanks,
Jeremy.