The dark side of heavy trading clung to online brokers as Wednesday was shaping up as a record volume day for the firms.

As brokers processed a deluge of trades, some customers were reporting problems trading online. These clogged systems are like the compromising photos celebrities try to hide on their way to the A-list -- the situation gets more dire the more popular the celebrity becomes.

Indeed, in the past weeks, the revenue-plumping effects of heavy trading volume have pushed up online brokerage stocks -- in some cases dramatically. But while shareholders watched in glee, enthusiastic trading created problems at some brokers, leaving customers unhappy. And with today's wild swing in the market and heavy volume, some online brokers continued to struggle.

"

Yesterday and today I have had trouble signing on my account," wrote

Waterhouse

customer J.C. Gadd in an email to

TSC

Wednesday. "I also get a message that says webBroker is down and that I can place an order over the phone."

Starting a week ago, Waterhouse, a unit of

Toronto Dominion Bank

(TD) - Get Report

, began periodically shutting down its online trading site

webBroker

to make sure it deals with orders accurately before and after they're executed, according to a spokeswoman. The firm began the procedure because of the heavy volume. Waterhouse said this morning that today was shaping up to be a record day. The site was down for about an hour Wednesday morning and for about 15 minutes Tuesday.

Users have been notified of the outages by a notice when they log in. Waterhouse is working to boost capacity in the part of the system that sends orders to be executed and returns them once they have been executed, said the spokeswoman.

Waterhouse isn't the only swamped broker. Over the past few days in email to

TSC

and on message boards, online traders have complained of slow site responses, problems with quotes and troubles accessing sites. And site problems typically produce loooong waits on the phone, stymieing timely trading. Most online traders write that branches aren't an option and don't fit with their trading style even if they were. Last

week,

Donaldson Lufkin & Jenrette

(DLJ)

unit

DLJdirect

and

Charles Schwab

(SCH)

said they had volume-related problems. Some customers of

E*Trade

(EGRP)

also have complained.

"I'm able to log on, but I haven't been able to access the Platinum Power E*Trade site for active traders," wrote Jim Dupree in an email Wednesday. Dupree, who had been having problems with E*Trade's site for the past couple of weeks, said the system seems better than yesterday. "As usual E*Trade can't handle the volume, and trading has slowed to crawl if at all," wrote Craig Schilling on a

Silicon Investor

E*Trade message board Wednesday.

But Lisa Nash, E*Trade's spokeswoman, said, "We are not experiencing strain in the system. Where the bottleneck is is at the market-makers." She said Wednesday looks to be a record volume day and that E*Trade began preparing for a spike in trading weeks ago. But market-makers, she said, need to focus on executing trades at the expense of timely trade confirmations, which is frustrating some customers. E*Trade said it's trying to help market-makers handle the volume and is improving capacity links with them. The broker also posted a notice on its site that volatility and extraordinary volume is causing a delay in market reports.

Ameritrade

(AMTD) - Get Report

customers have also complained in emails. The company said it has experienced delays because of volume.