What things frustrate you while you're writing? Multi-tasking isn't complex enough to describe a writer's day.

Every writer has experienced it in some form. You’re really on a roll, the words rolling from fingers onto the computer screen like easy cheese unto a saltine. It couldn’t be smoother. Then it happens, you can a call, an email, a letter, some wonderful contact about that query you sent out months ago. Of course you hoped for that call, but it couldn’t come at a worse moment. Your protagonist in your current work in progress is hanging by an emotional fingernail and now you must leave him or her to dangle. So you put the work aside, give it a look of longing because the next scene is as vivid at blue ray in your mind. You take out that older work, give a quick polish, and sent it off. But days have passed. That ball of accomplishment barreling down the hill reaches a level spot. The emotion spewing from your imagination to become written words has slowed to a something more resembling baby’s drool.
These interruptions are part of writer’s life. Handling them is an integral part of the business. Any one who is a successful writer must do more than multi-task. They have to compartmentalize their creative urges. Perhaps in the morning they have to write an amusing or informative blog to keep the readers coming back to their website. After doing so, they might post some excerpts or promos on their yahoo groups. And of course, a smart author will zip around leave some comments on other authors’ blogs and articles. Facebook, myspace, answering emails, all things that keep a writer from putting new words on the page.
Early in my writing career, I hated putting aside a work that was really rolling and taking on another task. Who am I kidding? I still hate it. Much as I want to hear, and I really, really do, back from my latest queries, I don’t like to put aside one work and look back at another. It means I have to move from the mind of one set of characters, from one fantasy world with all its rules and quirks, from one world-shattering crisis, back to a different one. And it’s not easy. One must make sure your hero is speaking in his voice, not the voice of the one you set aside. All those notes on hair color, coin of the realm, magical laws of the land, and fell creatures, must be studied and relearned so you don’t mix your worlds together. One time I found the name of my hero from a different book in the middle of a completely unconnected series. How did he get there? Careful with the editing interruptus.
Writers write because they love it. But some of us also hope to sell our work. To do so, one must learn the dance. Two steps forward in a new work, step back and take care of the older work, be it published or in the submission process, and still somehow keep our sanity. Try not to miss a step. And when your writing feet get fatigued, give them a break by putting the computer aside and read.