beagle housebreaking lapse

Question
My beagle, Maggie, is about two years old.  I adopted her last winter, and housebreaking was very difficult.  Crate training didn't work (she would poop and pee in the crate), but after A LOT of patience and a very consistent feeding/walking schedule, things got a lot better.  She's been doing really well since the summer.  Now that the weather's changed again, she seems to have had a relapse.  A few days ago we went out for a walk; she pooped, but didn't pee (which isn't that uncommon for our mid-day walk).  When we got inside, she ran straight to my bed and peed.  I caught her in the act and scolded her, but we've had problems ever since.  Our schedule hasn't changed - she goes out for a quick pee once in the morning after waking up.  She has breakfast and "hangs out" while I get ready for work.  Then we go for a walk.  Ever since the peeing-on-the-bed incident, she'll have her quick morning pee, but she won't go to the bathroom when we go for our walk.  Naturally, I come home to an accident in the afternoon (she pees and poops inside).
As I said, nothing about Maggie's routine or diet has changed except that the weather is cold and there's snow on the ground.  She's also been banned from the bed, but she still has her favorite chair and blanket.  Is this a weather-related problem, or possibly a power-struggle (because of the bed issue)?  I'm getting really frustrated and don't know what to do.  Leaving her in a crate during the day isn't an option, as that is very traumatic for her (she is a rescue dog ...) and only appears to make her confidence-level and attitude worse.  I hope you can help us!!

Answer
Most behavior problems call for a vet check.  Peeing on the bed at 2 years old does suggest it is really a challenge to your leadership.  She is spayed?

The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm