U2311H, Latitude E6400, DisplayPort issue

Hello all, I would like to report a problem with displayport connection that is damaging my computer.

I have a Dell Latitude E6400 laptop and Dell U2311h monitor, I got both for Christmas. First I used the standard VGA cable to connect the monitor to laptop. But then I bought a displayport cable (not a cheap one) just to take advantage of the better DP connection. But after that I started to have problems with time on my laptop (well,at the time I didn't suspect, that it could be the DP connection). The system time in OS (Windows 7) was changing randomly and it was different every time I powered on the laptop. I considered it a sw issue (time server), so I tried to debug it through Windows, but to no avail. After some time I went into BIOS and noticed that the date/time there is standing still and it was weird (like 33/13/2087 22:12:00 PM). I thought, maybe it's the CMOS battery. Then the laptop began to reboot sometimes when trying to boot the OS or hanged completely at boot (black dim screen, gray cursor). So after that I called the tech support and they sent me a tech to service the laptop. He replaced the motherboard completely and it worked well after that, the issue was gone (also the time in BIOS started to work) - he didn't replace the CMOS battery, so it wasn't a battery issue (it wasn't reported as a battery issue in BIOS or in tests neither). He repaired the laptop in the morning that thay, it worked ok after that, as I mentioned. I powered it on again in the evening that day and it was still ok. But after that I tried to power it on again later at night but the laptop was dead. It means that the power on button flicked blue and then it died. So I called the tech support again. They sent a tech, he replaced the motherboard again and it worked (again). But after that I was highly suspicious that something is seriously wrong in my setup (they told me that I was just unlucky, but it looked just too weird to me). Then I remebered, that I plugged in the monitor through DP connection in the evening that day. I told it to the tech, he said that it shouldn't be a problem. He told me only to check the DP cable if it isn't damaged. It wasn't and since it wasn't a cheap one.. So I plugged the DP cable, worked with the laptop, turned the laptop off.. and after I turned it on the time issue was back again ! Also in BIOS, the time was stuck. After that I was concerned thata it was the DP connection that fried the motherboard for 2 times. So I started to debug it (in a hw kind of way) and I noticed a high-pitched noise coming from the place of the DP port on the laptop (graphic card ?). Then I turned the laptop off, turned the monitor off, unplugged the laptop from wall (from AC adaptor) but I left the monitor plugged to wall (so it was still receiving the power while off). And guess what, the fan on the laptop was still turning (it was probably the fan of graphic card, not the main one). After I unplugged the DP cable, the fan stopped turning. I also can't get the laptop into suspend while it is connected to the monitor with DP cable. The monitor goes off, but the laptop is still on and the fan is turning like wild.

I have done some research on the web and it seems that this issue is caused by a certain type of DP cable (not by the monitor in this case, I guess). There is a pin 20 that is connected (is alive). This pin should deliver power to the device (I hope I am right in this, since I am no expert). But in some way I think it is causing short circuit (maybe) and damage to the computer. I read that there are some DP cables, that do not have this pin 20 (powerline) connected and they should work without problems.

The thing is, that this cable that I bought is made by quite a big European company and it is not a cheap junk. But if I knew that this kind of cable can cause trouble, I would certainly avoid it. So may question is to DELL : do you have some information that this kind of cables can cause damage to the devices you manufacture ? If yes, why don't you provide a "good" displayport cable with your monitors ? (you only provide VGA and DVI cables with U2311h).

Can you give me some advice which cable should I buy that would not damage my computer ? (which brand etc.)

Sorry for such a long post, but it had to be long. Hope someone will give a helping hand.

Filip