we have two seperate modules that work together.  one contains a search control (actually a series of controls that build a query) and one contains a grid (asp.net gridview).   the search is on the home page.  the user runs the search (clicking button , which loads imcsender from the control and redirecting to grid page) and it is successful.  hits the back button and then the searches again.  this time the search fails.  none of this happens in the ide (vs2005).  through logging we have determined that the control is not functioning after the page back.   after the button.click both the page load and button.click both show the selectedvalue of the ddl to be "" (string.empty) which is not even a value in the ddl.  it is -1, 1,2,3, etc.  the text in the ddl is visible and everything looks ok (although sometimes the value in the dll is selected and sometime "no value" or (-1) is displayed)

i have run into a very similar situation when a detail page is clicked to from the grid, the back button is clicked and then when paging is engaged, the grid pages but loses it format.  for this one though, i am able to check that the grid has lost it settings and reset them.

my feeling is that it is either a caching issue or an issue with view state or both.

we are using the default ServerAndNoCache which i beilieve is the one i want.

we just upgraded to 4.8.1 from 4.7.0 and don't think we were having these issues and we are a high volume site.