I bought a HP desktop computer recently. When I tried to open the case, I noticed that there is a seal at the bottom of the case. It states that opening it will void the warranty. What is that all about? I have bought many computers over 20 years but this is the first time I see this kind of seal on a desktop system. I certainly want to upgrade the computer myself. I tried to add 2GB more RAM to my system but the sales told me that HP does not sell it, I had to look for 3rd party. As I have experience in building several PCs, I don't want to bring my computer to the dealer and pay them to do the job.