1. Wrong: The murder in the tunnel created a nightmarish traffic jam nevertheless drivers waited patiently for more than an hour.
Better: The murder in the tunnel created a nightmarish traffic jam; nevertheless, drivers waited patiently for more than an hour.
Explanation: Nevertheless, a conjunctive adverb, can't join these two independent clauses into one sentence, so a semicolon is needed.
2. Wrong: For many years, The Wizard of Oz was the all-time favorite movie at one time, every kid on my block wore ruby slippers.
Better: For many years, The Wizard of Oz was the all-time favorite movie; at one time, every kid on my block wore ruby slippers.
Explanation: The first version leaves two complete sentences joined as if they were one sentence. This kind of error is called a run on.
3. Wrong: When the tiny babies started to appear around campus, everyone loved finding them, nobody knew who kept putting them up.
Better: When the tiny babies started to appear around campus, everyone loved finding them. Nobody knew who kept putting them up.
Explanation: These are complete sentences joined by a comma. The error is called a comma splice.
4. Wrong: My daughter said we needed another dog to keep us company, we already have six dogs.
Better: Although we already have six dogs, my daughter said we needed another dog to keep us company.
Explanation: Two complete sentences, joined by a comma creates an error called a comma splice.
5. Wrong: She gave good advice, she told us all to look up and look around.
Better: She gave good advice: she told us all to look up and look around.
Explanation: You can join these two complete sentences with a colon because the second one provides a definition for the last word in the first one.