Updated from 2:50 p.m. EDT

Microsoft

(MSFT) - Get Report

fell in active trading Monday after confirming that its next major Windows upgrade will ship in 2006 without a long-awaited hard-drive filing function. While most analysts said the news was already reflected in Microsoft's price, which is 20 times the 2006 First Call estimate, the shares closed down 16 cents, or 0.6%, to $27.30 on typically high volume of 36 million shares.

Intel

(INTC) - Get Report

closed down 42 cents, or 1.9%, to $21.60, in sympathy.

Ballard Power

(BLDP) - Get Report

rose 11%, while

Plug Power

(PLUG) - Get Report

tacked on 1.7% ahead of an Energy Department announcement on how $77 million will be divided up for hydrogen-power research over the next year. The companies develop fuel cells, which incorporate hydrogen as a possible alternative source of energy for cars. Shares of Ballard, which traded up 65 cents to $6.51, and Plug, which traded up 11 cents to $6.33, often swing wildly with any development in their space.

United Rentals

(URI) - Get Report

fell 21.5% after disclosing that the

Securities and Exchange Commission

began a fact-finding probe of unspecified issues at the company that included a subpoena for certain accounting records. United Rentals said it's cooperating with the probe. The stock closed down $4.39 to $16.

Chiron

( CHIR) extended the

slide it began Friday on news of a delay in its flu vaccine Fluvirin, and was joined Monday by most of the biotech sector. The stock, which closed at $47.49 Thursday, traded down Monday 83 cents, or 1.9%, to $42.58. Other weak biotech names included

Genentech

( DNA), down $1.50, or 3%, to $48.40;

Amgen

(AMGN) - Get Report

, down 67 cents, or 1.1%, to $59.01;

Biogen-Idec

(BIIB) - Get Report

, down $1.83, or 3%, to $58.63; and

MedImmune

( MEDI), down 73 cents, or 3%, to $23.76. MedImmune shares slipped after the company discontinued trials of its Vitaxin in patients with rheumatoid arthritis and psoriasis.

ImClone

(IMCL)

fell after pharmaceuticals industry group IMS Health estimated that ImClone

sold $25.4 million worth of its cancer drug Erbitux in July. That's down from $30.1 million in June, a trend that had some on Wall Street worried that Erbitux's gangbusters open was related to a demand glut. The stock closed down $4.03, or 7.2%, to $51.97.

LNR Property

( LNR) rose after buyout firm Cerberus Capital agreed to take the company private for $1.9 billion plus assumed debt. The

Lennar

(LEN) - Get Report

spinoff, which is controlled by Chairman Stuart Miller, was sold for $63.10 a share in cash. The stock traded up $3.71, or 6.3%, to $62.81.