There are multiple bands called Warning.

1) Warning was a doom metal band formed in Harlow, Essex, England, UK, formed in 1994 by Patrick Walker and Stuart Springthorpe. They were notable for their slow, progressive, melodic, heavy and doom-laden sound; the idiosyncratic and poignant vocals of Patrick Walker; and his introspective, darkly confessional lyrical themes.
The band released two demo tapes, Revelation Looms in February 1996 and Blessed by the Sabbath in March 1997 which led them to gain underground metal press attention and label interest. Warning's debut album The Strength to Dream was released in 1999 via The Miskatonic Foundation (owned and run by Richard M. Walker of Solstice). With this album Warning gained a cult status within doom metal circles, but they soon disbanded after their 2001 European tour with Jack Frost. They regrouped in 2004 to write new songs and to perform at The Doom Shall Rise festival (Germany) in 2005, and released a second album Watching From a Distance (also via The Miskatonic Foundation) in 2006 to wide acclaim.
Both albums were re-issued on CD in 2008 by the label Cyclone Empire, The Strength to Dream being re-packaged in new sleeve artwork. Similarly the albums were released by the Metal Supremacy label as gatefold double-vinyl editions limited to 500 copies each, 125 of each pressed on coloured vinyl.
In 2008 Stuart Springthorpe left the band due to family and work commitments but continues to teach drums and perform. Patrick Walker decided to discontinue the band in January 2009 and continues to write and record music with his new band, 40 Watt Sun.

2) Warning was an electro / synth rock duo from Hamburg, Germany, formed by Ed Vanguard (Edgar Schlepper) and Mike Yonder (Hans Müller). The group was active between 1982-1983, and had a one-hit-wonder with a song from the episode "Peggy Hat Angst" from the German TV Series "Tatort".

3) Warning was a heavy metal band from Sweden, active between 1987-1989.

4) Warning was a heavy metal / speed metal band from France, active between 1979-1983.

5) Warning is a power metal band from Dąbrowa Górnicza, Poland, formed in 2003. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.