Mark,
There seems to be an issue with unhiding sold investments. I view it as a bug, but you might see it as a suggestion.
I've run FILE OPERATIONS/HIDE SOLD INVESTMENTS with a date range 12/31/10 to 3/31/11. I have an investment which had 0 shares 12/31/10, then bought and sold shares on the same day in Jan 2011. It therefore has 0 shares on 3/31/11 (and as of the end of day every day in the date range). I've got "UnHide Non-Sold Investments" checked. This one stays hidden, I guess because you are looking at end of day balances. I think this investment should be un-hidden since it did have a balance/activity during the period --just not end of day.
Now that I think about it, I guess something that paid a dividend received after the position was sold out could also stay hidden (and I think it should un-hide). Maybe you need an additional option to cover "any transaction" during the selected period in addition to looking at end of day balances.
Elliot