All tests were executed in the following environment:
Camera: standard ToUcam; Format 640x480; Duration 300 seconds
Active background programs: IE, Outlook, McAfee, Excel
Laptop: Asus L5800GX Pentium 4, 3.2Ghz, HDD 80GB 5400 RPM, 512MB DDR
Software: Win XP Pro SP II and K3CCDTools 2, release

Mode Speed Frames captured Dropped frames Remarks K3CCDTools
WDM 5 fps 1500 5 1) Only frames 1,2,3,4,5 were dropped 1) Click
WDM 10 fps 3000 5 1) + 676 2) Frames 1,2,3,4,5 were dropped 1) and all frames starting from frame 2324 onwards 2) Click
WDM 15 fps 4500 5 1) + 2176 2) Frames 1,2,3,4,5 were dropped 1) and all frames starting from frame 2324 onwards 2) Click
VFW 5 fps 1500 0 None Click
VFW 10 fps 2995 0 None Click
VFW 15 fps 4501 1 Only frame 2 was dropped.
Note: I had to restart K3CCDTools, because when capturing the first AVI a McAfee update arrived via the open internet connection, which caused K3CCDTools to stop responding.
Lesson learned: close internet connection when capturing.

1) Checking the box 'Capture startup message box' (Settings|Video Capture) greatly reduces the Dropped Frames at the start of the AVI.

2) K3CCDTools author and owner Peter Katreniak commented: " the frames in your long sequences (rows 2 and 3 of your table) are not really dropped. They are reported as dropped by K3CCDTools, because the AVI generated by WDM is generated according to new AVI standard, which enables to have AVI files longer than 2GB.
The disadvantage of such AVI files is, that they have "2GB barrier" for standard AVI reading programs."

Note from Jan Timmermans:
K3CCDTools version 3 processes huge AVIs without any problem; see my Planetary Post Processing Tutorial
From version 5 onwards Registax also has no problems with files of over 2 Gigabytes.

Important: in my observatory I have 220 Volt available and of course my laptop is connected to the mains.
However it is a known fact that laptops running at lower voltages (from a car battery etc.) suffer badly from dropped frames, especially at higher fps rates.

Use the proper USB cables
As the USB cable of the Trust WB-5400 is rather short you may want to use an extension cable. Make sure that you use a USB 2.0 cable or else you will have LOTS of dropped frames, especially when imaging in 1280x1024 pixel mode [I had 75% dropped frames]. With a 3 metres USB 2.0 extension cable I had zero dropped frames.

In really cold winters you should pay attention to the health of your computer, because low temperatures do have a negative impact on the performance of your hard disk drive thus resulting in very slow boot up and ... high volumes of dropped frames.
Here is what Norwegian Carsten Arnholm says:
I have operated my laptops without problems down to -20C. But notice I always:
- keep my computers inside the house when not observing
- run the computer on 220V AC power outside, never on battery
- boot the computer immediately after going out
- take care of of humidity issues after bringing the computer inside after a very cold session.

Cold air is dry, warm air is humid. If you bring optics or electronics inside from the cold you should always put it in a plastic bag before going inside, then let it warm up without opening the bag. That way dew will not accumulate.

In short cold weather is not a problem for computers if you take such precautions, humidity is worse.
If you want to keep the computer outside for a long time in the cold, never shut it down.
The heat it generates will make sure dew/humidity is not a problem.

Some other hints:
- Make sure you have enough free disk space (including the space used by Windows as swap area)
- Defragment
- Make sure that the frame rate (fps) of your camera and the settings in K3CCDTools are identical
- Use lower fps rate
- Close the virus scanner and all other unnecessary programs