How to close all, or only some, tabs in Safari using AppleScript?

I have made a very simple AppleScript to close tabs in Safari. The problem is, it works, but not completely. Only a couple of tabs are closed. Here's the code:

tell application "Safari"
    repeat with aWindow in windows
        repeat with aTab in tabs of aWindow
            if [some condition is encountered] then
                aTab close
            end if
        end repeat
    end repeat
end tell

I've also tried this script:

tell application "Safari"
    repeat with i from 0 to the number of items in windows
        set aWindow to item i of windows
        repeat with j from 0 to the number of tabs in aWindow
            set aTab to item j of tabs of aWindow
            if [some condition is encountered] then
                aTab close
            end if
        end repeat
    end repeat
end tell

... but it does not work either (same behavior).

I tried that on my system (MacBook Pro jan 2008), as well as on a Mac Pro G5 under Tiger and the script fails on both, albeit with a much less descriptive error on Tiger.

Running the script a few times closes a few tab each time until none is left, but always fails with the same error after closing a few tabs. Under Leopard I get an out of bounds error. Since I am using fast enumeration (not using "repeat from 0 to number of items in windows") I don't see how I can get an out of bounds error with this...

My goal is to use the Cocoa Scripting Bridge to close tabs in Safari from my Objective-C Cocoa application but the Scripting Bridge fails in the same manner. The non-deletable tabs show as NULL in the Xcode debugger, while the other tabs are valid objects from which I can get values back (such as their title). In fact I tried with the Scripting Bridge first then told myself why not try this directly in AppleScript and I was surprised to see the same results.

I must have a glaring omission or something in there... (seems like a bug in Safari AppleScript support to me... :S) I've used repeat loops and Obj-C 2.0 fast enumeration to iterate through collections before with zero problems, so I really don't see what's wrong here.

Anyone can help?

Thanks in advance!

this works for me nice and simple

  tell application "Safari"
    close every window
  end tell

ok you have to go from the count to 1 otherwise the count will be off when you close the window

  tell application "Safari"
    repeat with i from (count of windows) to 1 by -1
        repeat with j from (count of tabs of window i) to 1 by -1
            set thistab to tab j of window i
            set foo to name of thistab
            if foo is not equal to "bar" then close thistab
        end repeat
    end repeat
  end tell