Fixed Duration problem ? (Enterprise version)

Has anyone encountered a problem with a fixed duration task, what is happening is that I have a task that is fixed duration non effort driven for 50 days I then assign resources at let us say with 50 hours of work, it then populates out the 50 days with 1 hr work per day. But once the first actuals are accepted through Project Web Access then all the remaning work for that resource is lumped into the next day. to fix I have to remove the remaning work and then re type it in, then it is once again levelled over the remaning duration.
Any help would be appreciated G.