Yes, but it won't be as serious as WWII was.
My possible scenarios are:
1. the war in Iraq blows out of proportion with the USA launching major attacks on Iraq. Iraq retaliates with terrorist attacks in major US cities. Russia and/or China sides with the Middle East in the fight against the USA. Canada, Britain, Germany, Japan, etc. all side with the USA.
2. More of a Korean War Part 2 then WWIII but North Korea attacks south korea; possibly with nuclear weapons. I have China siding with North Korea (both communist) and everyone else helping South Korea, even Russia.
3. India vs. Pakistan becomes a full scale war with the exception of the USA either not being involved, or very minimally affecting the outcome. All the Islamic countries will side with Pakistan and either India will be on their own or the allies (Europe) will help them.
4. Straight up war between China and USA. I have Europe helping USA and Russia/Middle East helping China.
5. Germany decides "third time's a charm"...j/k