I wrote:
So maybe the solution is indeed as simple as that.

Or not. Happened again, despite the 100-msec sleep, closing all extraneous
windows, and minimizing the Excel window.


----- original message -----

"Joe User" <joeu2004 wrote in message
...
"Homey" <none wrote in message
...
how excel is sometime whn you use
screenupdating = false.

I 'spose I could try that. But I would not think it would change anything
because: (a) the long-running macro is not modifying or even accessing
the worksheet; and (b) non-Excel windows are also affected adversely.

The other open, but background windows were Outlook Express and Notepad,
for sure. I might have also had some IE windows open, accessing some web
pages. I think the web pages were benign. But if any of those were Google
web pages, there could be "a lot" of activity going on, even though they
are in the backgound.

I did increase my sleep time to 100 msec every 1+ sec. And I closed all
windows except the Excel and VBA windows. The CPU-intensive macro ran for
45 min without affecting the system adversely.

So maybe the solution is indeed as simple as that.


----- original message -----

"Homey" <none wrote in message
...
i see this happen many times for many years. i don't like it but it never
seem to do anything bad so i just say that how excel is sometime whn you
use
screenupdating = false.


"Joe User" <joeu2004 wrote in message
...
|I am using WinXP SP3 and Excel 2003 SP3 with VBA 6.5.
|
|
| I have a long-running macro that is CPU-intensive. However, about
every 1
| sec, I log some information and sleep for 20 msec.
|
| After "a while" (it varies), one or more open windows go blank. That
is,
| there is nothing but white inside the window frame. Moreover, my VBA
window
| is no longer the active window -- none is.
|
| When I log to the Immediate Window, that window goes blank very soon,
often
| as soon as one page is filled (i.e. the window scrolls).
|
| But this also happens when I log to a file -- and this time, it
happened
to
| all windows, foreground and background. (I had walked away from the
| computer for about 45 min.)
|
| The system is still responsive. When I "break" and end the macro,
| everything is usually restored to normal. But it is still
disconcerting.
|
| Any idea why that happens? Any idea how I can avoid it?
|
| I suspect this is really a WinXP issue. Any idea what NG would be
monitored
| by responsive people who are knowledgable in this area (the O/S)?
|
| I've tried posting such technical questions to m.p.windowsxp.general in
the
| past. The response are usually not impressive.
|
| I have extensive O/S background, albeit not with MS Windows. 20 msec
is
| usually at least two "ticks" (about 33 msec on WinXP). That is usually
| plenty of time to run other non-CPU-intensive processes, e.g. for
window
| updates and timer-based bookkeeping.
|
| Nonetheless, in other circumstances, I have extended the sleep to as
much
as
| 1 sec, to no avail.
|