Windows warns me not to use ebay! ("security certificate" problem--is this real?

I have never, ever used ebay before. What did I do wrong, and why am I being spanked for it?
I found an item I want to buy, available only on an ebay store. So I spend a couple hours trying to figure out how paypal works, & I open a paypal account
So far, so good… I’m smugly thinking, “hey, I’m as web-savvy as the grandkids”

I go back to ebay, and find my store.
I click on “Buy it now”.
I face two options: 1) register, or 2) “make your first purchase as a guest shopper”
I click on the ‘guest shopper’ option

Suddenly, a new window opens up, labelled “ERROR:naviagtion blocked–Windows I.Explorer”
The window warns me “there is a problem with this website’s security certificate.The security certificate presented by this website was issued from a different website’s address.We recommend that you do not continue”
What is wrong here? I thought ebay was respectable…
My question to you ebay-smart folks is: should I continue doing business with this site? Or am I doing something wrong? Is there a workaround, by , I dunno, registering with ebay or something?

(more info:
The site I went to on ebay was a “real” a store that closed down its brick-and-mortar business,and now sells only through the internet.(the store is a pretty small niche–it sells kaleidoscopes to collectors) It was recommended to me in a phone call to the owner of a similar store which still has its brick and mortar doors open)

I didn’t click on a phishing email…I typed in “www.Ebay.com” and then navigated to my store. It looks legit to me… I eventually ended up at a page with the following (incredibly long!) info in the address bar of my IE8 browser:.

https://signin.ebay. com/ws/eBayISAPI.dll?SignIn&ru=http%3A%2F%2Foffer.ebay.com%2Fws%2FeBayISAPI.dll%3FBinConfirm%26item%3D190109200315%26pt%3DLH_DefaultDomain_0%26quantity%3D1%26fb%3D1%26frompage%3D4340%26rev%3D0%26BidBinInfo%3D%253CbidInfo%253E%253CID%253E190109200315%253C%252FID%253E%253CMB%253E%253C%252FMB%253E%253CQTY%253E1%253C%252FQTY%253E%253C%252FbidInfo%253E&pageType=2143&onepagereg=1&item=190109200315&ICurl=https%3A%2F%2Fsecureimg.ebayimg.com%2Fi10%2F02%2Fi%2F05%2F6a%2F3c%2F7b_0.JPG&ICtitle=The+Kaleidoscope+Collector%27s+Guide%2C+NEW%2C+1st+ed.&ICdateMedium=Oct-18-09&ICtimeLong=10%3A50%3A28+PDT&gch=1&gchru=https%3A%2F%2Fpayments.ebay.com%2Fws%2FeBayISAPI.dll%3FGuestCheckoutProcessor%26item%3D190109200315%26quantity%3D1%26transactionid%3D-1%26rev%3D0

Sometimes websites just neglect their security certificates. I’ve gotten several warnings at various websites that had expired or improperly configured certificates. If you’re sure you’re at ebay.com and not a phishing site, you should be fine.

Ive seen that error sometimes when the certificate is expecting www.ebay.com instead of ebay.com. Try visiting www.ebay.com. If it continues then you may be experiencing a man in the middle attack or something has edited your hosts file or DNS server. Ot it could be ebay slacking on its certificates, but am Im not getting the error when I try to log in.

Also make sure your clock on your PC is set to the correct time, year, and time zone.